Recommended Components

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ampsandsound Bigger Ben: $5600
This single-input, single-ended, triode-wired, no-negative-feedback tube amplifier drives both loudspeakers and headphones. It offers approximately 8Wpc into 8 ohms and 5Wpc into 32 ohms (when equipped with a solid state rectifier and KT88 output tubes). With 6L6GC output tubes, when it maxes out at 3Wpc, the Bigger Ben powered Zu Soul Supreme speakers "to greater levels of transient and timbral exactitude … than most any other amp I've tried," wrote HR. With DeVore Orangutan O/93s, HR found the Ben every bit as natural and engaging as the First Watt F8 and Elekit TU-8600. Driving HiFiMan's hard-to-drive Susvara headphones, HR described the Bigger Ben as having a radiant quality—"as if the sound were illuminated from within." Rated A+ as a headphone amp. (Vol.44 No.4 WWW)

Anthem STR: $4999 ★ $$$
Anthem's solid state STR integrated amp offers 200Wpc (into 8 ohms) of class-AB power, along with seven analog inputs—one balanced, four single-ended, and two phono (one MM, one MC). It also offers a 32-bit/192kHz D/A processor with six digital inputs—four S/PDIF (two RCA, two TosLink), one AES/EBU (XLR), and one USB. A subwoofer output is provided, but, curiously, there's no headphone output. Of interest to users with problematic listening rooms is the STR's built-in Anthem Room Correction (ARC) processor: using the supplied microphone, ARC can be set up using a PC that's been configured with the appropriate (downloadable) software and connected to the Anthem's miniUSB or Ethernet jack. (The latter has no other function: the STR is not Wi-Fi capable.) Even before setting up and trying ARC, TJN enjoyed the Anthem STR for sounding, with one recording in particular, "punchy and likely true to the source, with excellent detail and an open midrange." With ARC engaged, TJN heard differences that "ranged from subtle to striking … and were only rarely inconsequential." Benefits included a "cleaned up" double-bass sound on one CD, greater upper-bass precision in the sounds of massed voices on another. His conclusion: "a watershed product worth serious consideration." Writing of his experiences in measuring the Anthem STR, JA called it "a well-engineered amplifier offering high powers and respectable measured performance." (Vol.41 No.7 WWW)

ASR Emitter II Exclusive: $33,000 ★
The four-box, solid state Emitter II Exclusive—five boxes if you count the chunky, Corian-encased remote handset—weighs over 300lb total, largely (haw) for the number of outsize frame-style transformers it uses. The separate boxes include the amp itself—which is over 22" wide—plus two outboard power supplies and one outboard battery power supply, plus automated charging system for the amp's input circuitry. And that handset. Technical highlights of the 250Wpc (into 8 ohms), class-AB Emitter II Exclusive include input and output sections whose every active device is mechanically isolated, a variable-gain volume-control system actuated by a rotary encoder, and internal switches for tailoring most performance variables to the user's system; nontechnical highlights include a physical design unlike that of any other audio product, elements of which AD found "strangely beautiful," plus documentation, ergonomics, and a gestalt that had AD reaching for the L-word (as in love, not inductance). Through his DeVore Fidelity Orangutan O/93s, the ASR produced a grand sense of scale, a very good sense of flesh and blood, and stirring musicality; from AD's Quad ESLs the ASR teased momentum, clarity, touch, impact, electronic gunklessness, and the snappiest bass he's ever heard from those speakers. Art concluded that the ASR is "a very complex product that somehow manages to sound very simple." A great, unique integrated amplifier, and a must-hear for ESL owners. (Vol.41 No.8 WWW)

AVM Ovation A 6.2 ME: $8495
Full-featured, German-made integrated includes balanced and single-ended inputs, all with adjustable sensitivity, a high-resolution "digital" volume control, tone controls, and a discrete headphone output. Runs hot due to the MOSFET output stage being heavily biased into partial class-A operation. HR felt that the A 6.2 ME "imparted a sense of polish, or 'wetness'" to the "almost-dry-but-not-dry sound" of the Falcon "Gold Badge" LS3/5a's. Compared with his long-term reference, the Rogue Sphinx V3, HR commented that the AVM "lit up the music, making it brighter, more vivacious, more right there in front of me, more pacey, and—I think—more meaningful." AVM specifies the A 6.2 ME's maximum output power as 180Wpc into 8 ohms and 300Wpc into 4 ohms. With both channels driven the Ovation delivered 190Wpc into 8 ohms and 315Wpc into 4 ohms. HR liked the sound of the headphone amplifier with sensitive headphones but found that it struggled to deliver undistorted power into the HiFiMan Susvara's difficult load. JA's measurements confirmed that the headphone output clipped at a relatively low voltage, but he wondered if this problem was specific to the review sample. (Vol.44 No.6 WWW)

Ayre Acoustics EX-8 2.0 Integrated Hub: $6450–$8350
JA reviewed the original version of this integrated amplifier, which had an onboard D/A processor and a Roon-Ready Ethernet port, in the February and April 2019 issues of Stereophile. The 2.0 version's 100Wpc output section still features Ayre's feedback-free Diamond circuit, but it doubles the number of output devices, allowing it to drive more difficult loads and increasing its power output into 2 and 4 ohm loads. (JA measured clipping powers of 107Wpc into 8 ohms and the specified 170Wpc into 4 ohms, compared with the original EX-8's 125Wpc into this load.) Listening to LPs with an external Tavish phono preamp feeding the Ayre's line inputs, KM wrote that the EX-8 2.0 is "one sweet honey of an integrated amplifier. … Its outstanding sonic trait is its focused, pristine clarity, a gently scrubbed vision that frames music with refinement, richness, and lucidity." Turning to digital, he wrote that "the trademark Ayre sweetness imbued deep organ notes and electric bass with lushness. An upper-midrange-to-treble crispness aided vocals and guitars, with excellent sustain." He did note that the EX-8 2.0 had a "first row" perspective but concluded that "with its pure treble, clear and rich midrange, ample low end, and coherence, the Ayre is the finest solid state integrated I've had in my house." Analog-only price is $6450; S/PDIF and AES3 inputs add $1000; USB input adds another $500; Ethernet port adds $1700 to base price; fully loaded version costs $8350. (Original version, Vol.42 Nos.2 & 4, WWW; 2.0 version, Vol.44 Nos.11 & 12 WWW)

Bel Canto Design Black ACI 600: $25,000 ★
No mere integrated amplifier—designer John Stronczer claims that his product "diverges from traditional architectures"—the Bel Canto Black ACI 600 is, in essence, the combination of a 24-bit/192kHz D/A converter with a 300Wpc class-D amplifier, the latter constructed with NCore modules. Also featured are a phono stage with MM and MC inputs, digital bass-management controls, circuitry for unfolding MQA files, and Seek, an iOS-based app for streaming music from Tidal—although, at the time of his review, JVS described Seek's instructions as inadequate. Happily, the sound was anything but: "Once fully warmed up, the Black ACI 600 shattered all notions of class-D sounding colorless and uninviting," wrote JVS, though "treble extension was a bit toned-down from what I'm accustomed to." His conclusion: "That this single box can do so much so well … should earn it pride of place in many a system." Writing from his test bench, JA noted the Bel Canto's difficulties with 384kHz files, but found it exceeded its power rating into 8 ohms, fell a bit short into 4 ohms, and evinced "respectable measured performance" overall. (Vol.41 No.4 WWW)

Boulder 866: $13,450; $14,950 with streaming DAC
This beautiful-looking, made-in-America, powerful integrated amplifier features a class-AB output stage that is heavily biased into partial class-A operation. As a result, it runs very hot and needs to be given adequate ventilation. Analog inputs are all balanced; the optional digital-input module adds Ethernet, USB, AES3, optical S/PDIF, and Wi-Fi. JVS was impressed by the 866's analog inputs. While the 866 couldn't produce a soundstage as wide as his big monoblocks do, its bass wasn't as firm as that of more powerful, more expensive amplifiers, and it couldn't deliver ultimate transparency, "the music's essential color palette, and its message, were as captivating as they are with any equipment. … I felt I could trust the Boulder 866 to be there for me, time after time, delivering sonic truth." Playing music with the Boulder's Ethernet input and Roon, JVS felt that the 866 sounded far better than he expected a $1500 DAC to sound, with a wider soundstage than he was anticipating. He concluded that "the quality of its optional DAC blew me away." Measured performance with the analog inputs was superb, with excellent channel separation, very low noise, and low, predominantly third-harmonic distortion. With both channels driven, the 866 exceeded its specified maximum power into 8 ohms of 200Wpc, clipping at 1% THD+noise at 210Wpc. As is often the case with integrated amplifiers the 866's digital inputs had too much gain, but offer just above 18 bits' of resolution. Class A rating applies to use with analog inputs only. (Vol.44 No.9 WWW)

Cambridge Audio Edge A: $6000 ★
Created in time for Cambridge Audio's 50th anniversary, the Edge A charts newish territory: a combination D/A processor-integrated amplifier designed and built to perfectionist standards, offered at a considerable though less-than-extortionate price. Boasting both digital and line-level analog inputs, the Edge A is specified to deliver 100Wpc, operating in what Cambridge calls class-XA, described as less efficient than class-AB but more efficient than class-A. This "seriously beautiful piece of hi-fi" seduced KM with the "creamy" feel of its large, dual-function (volume and source-selection) control knob and sealed the deal with bass notes that were "clean and round, a little dry," and spatial performance characterized by "some of the best soundstaging I've heard in my apartment." Writing from his test bench, JA noted power output (145Wpc into 8 ohms) that "handily exceeded the specs" and "superb measured performance in both the analog and digital domains." In a Follow-Up describing his listening impressions, JA praised the amp as "a sonic powerhouse." Ken's conclusion: "I'd say it's worth your time and your $5000." (Vol.42 Nos.1 & 4 WWW)

CH Precision I1 Universal Integrated Amplifier: $38,000–$53,000 ★
CH Precision's decidedly modular I1 Universal integrated amp–D/A processor can be had with a variety of extra-cost options, including a USB digital-input board, an Ethernet-input streaming board, an MC phono-input board (with more EQ curves than just RIAA), and a clock-synchronization board that permits the use of an outboard digital clock. In its base form ($38,000), the I1 provides one pair each of balanced (XLR) and unbalanced (RCA) analog inputs, plus an S/PDIF digital-input board and two balanced (XLR) stereo outputs. Echoing the future-proof design of the amp itself is the I1's D/A processor, which is coded into a field-programmable gate array (FPGA); this upsamples 16-bit/44.1kHz PCM and its multiples to 24/352, and 16/48 PCM to 24/384. The I1 handles up to DSD2565, and converts all DSD data to 24/352.8 before playback. Its class-AB output section can provide up to 100Wpc into 8 ohms. Notwithstanding some setup complexities, JVS was able to get from the I1 "some mighty impressive sound," and to the extent it fell short of his own (costlier) reference gear, those were "sins of omission rather than of commission." JVS found the CH Precision's sound to be "clean, strong, and direct," yet it did not "filter out those intangibles that allow the music to elicit a powerfully emotional response." His verdict: "one of the most complete, most neutral sounding, most carefully conceived components I've reviewed." Writing from his test bench, JA praised the I1's "excellent measured performance." (Vol.42 No.2 WWW)

Decware Zen Triode Amplifier: $999 $$$ Decware 25th Anniversary Zen Triode Amplifier: $2995 without tubes; $3395 with "curated" tubeset
The 2.3Wpc Zen Triode is a class-A, zero-feedback, single-ended stereo tube amplifier that uses just two resistors and one Jupiter Beeswax film capacitor in its signal path. The output tube is a triode-wired, self-biasing, self-balancing 6N15N (equivalent to a 6BQ5/EL84). The voltage amplification tube is a 6H1N/6N1P dual triode (equivalent to a 6922/6DJ8). With the Denafrips Ares II DAC and Klipsch RP-600M loudspeakers, HR noted a "conspicuous purity of sound" resulting in one of his "most thought- and pleasure-filled musical moments of 2020." "With the Zen's bias switch on High," he added, "music from the RP-600Ms was reproduced with a level of overt vividosity that I had not experienced previously." The considerably more expensive 25th Anniversary Zen Triode Amplifier features an African Padauk hardwood plinth, gold-plated switches, super-duty gold-plated tube sockets, NOS Western Electric Milliamp meters, a choice of knobs for the dual-mono volume controls, and three independent, tube-regulated power supplies, one for each tube. "Without 100dB/W/m horns, the Zen Triode will not crush rocks or destroy planets," HR wrote. "But driving the modest Zu Audio Soul Supremes, it will play Mahler's Symphony No.5 as performed by the Berlin Philharmoniker under the baton of Sir Simon Rattle … with dark, moody vigor and delicious, microdetailed insights." (Vol.44 No.3 WWW)

Devialet Expert 140 Pro: $6500
Two years after his first Devialet experience—sharing a Paris apartment with two Gold Phantom speakers—Jim Austin spent time with the manufacturer's integrated, the Expert Pro, in entry-level guise. Essentially a 140Wpc integrated amp with a built-in streaming DAC, the Devialet utilizes a unique output section that links Class-D with class-A circuitry that, in the manufacturer's words, "corrects and completes" the signal. Support for Roon, Qobuz, and Tidal—the latter two via UPnP—is also built in. The Expert 140 Pro comes with an "unusual" remote control—a large volume knob and three small buttons; alternatively, the user can download Devialet's smartphone/tablet-friendly Devialet Expert Remote app. Only one analog input (RCA) is provided, and it can be programmed to serve as an MM/MC phono stage—although all incoming signals are processed in the digital domain. JCA noted the amp's "remarkable sense of openness," combined with "impressive" bass weight and a pleasing freedom from editorializing: "It [was] honest, evenhanded, liquid, open." Apart from bemoaning its "complex" setup scheme, JCA considered the Expert 140 Pro "an easy recommendation." Technical Editor JA admired the DAC section's "almost 20 bits worth of resolution," but he noted higher than expected levels of background noise. (Vol.42 No.12)

European Audio Team E-Glo I: $12,999 and up, depending on tube complement
This elegant-looking integrated amplifier uses a 12AX7 and a 12AT7 signal tube and a pair of KT88 tubes for each channel. There are two output transformer taps, optimized for 4 or 8 ohm loudspeakers. Specified maximum power is 35Wpc into 4–8 ohms in Ultralinear mode or 18Wpc into 4–8 ohms in triode mode, which JA's measurements confirmed, though at a slightly higher level of THD+noise than the Stereophile-standard 1%. With his DeVore O/93 speakers driven from the 8 ohm outputs, KM wrote that the E-Glo I's sound was "vivid, fast, forceful, clean, very open, spacious, transparent, dynamic, resolving, and full-bodied—even full-blooded. It served up good helpings of what Art Dudley called 'drive.'" KM preferred triode mode, finding that while Ultralinear made the sound more immediate and upfront, there was "a smidgen's loss of delicacy." Summing up, he wrote that "In its ability to create a supercharged musical presentation within a large soundstage populated by big images, allied to superb definition and resolution, with good tone, the E.A.T. E-Glo I gets so many things right in such a balanced, forceful presentation that I'd say it's worth its asking price." (Vol.43 No.12 WWW)

Grandinote Shinai: $15,000
Echoing tube-amplifier topologies, the Italian, dual-mono, fully balanced Shinai features two single-ended, class-A, solid state output stages in a push-pull arrangement for each channel, with no loop negative feedback. "As long as I am Grandinote boss," designer Massimiliano Magri told RS, "feedback will be prohibited like sincerity in politics." RS liked what he heard from this unique amplifier: "The Shinai made aural space microscopically tangible," he wrote, adding that the amplifier has "a knack for detail retrieval" and "gave notes and musical lines enough space to stretch out and seamlessly transition into the next notes and musical lines." This transparency was achieved without the presentation sounding clinical or etched: "The Shinai has the spirit of a revealer. It speaks the truth—not ruthlessly, but honestly." In the test lab, the Shinai almost met its specified maximum power of 37Wpc into 8 ohms at 3% THD+N, though JA warned against using the Grandinote with speakers whose impedance dropped below 4 ohms. JA summed up the measured performance by saying that it "is dominated by the designer's decision not to use negative feedback. I would expect the Shinai's sonic character therefore to be similar to that of a typical tube amplifier." However, RS concluded that the Shinai "did some things better than my tube gear—definition, detail, space, scale, touch." Two months after he submitted his review, RS was astonished to find that the Shinai's sound exploded: "It blew open musically. As good as it was already, the sound went from here up to there, overnight." An enigma, but lengthy listening sessions confirmed his impression. He concluded that the Shinai sounded "rich and bloomy but with a sense that you're hearing the true, original thing and not a recording." (Vol.43 No.11, Vol.44 No.4 WWW)

Jadis Orchestra Black: $4995
Derived from the Jadis Orchestra Reference Mk.II integrated amplifier ($4795) that AD reviewed in December 2015, the Orchestra Black is a less-expensive version developed for the US market. It retains the Mk.II's mostly hard-wired circuitry and the fixed bias for each channel's push-pull pair of 6CA7/EL34 power pentodes but uses transistors to provide voltage gain. AD wrote that the Black initially had "that treble lisp that I assume many of you have heard from amps and preamps that aren't yet run in—audible here as an exaggeration of note attacks from violins," but found that as the amplifier broke in, it became considerably more listenable, though still slightly on the dry side. He commented on how the amplifier complemented the sound of the harp: "Each plucked note had pretty good—not top-shelf, but perfectly satisfying—physicality of attack, but even better decays: maybe a slight bit too much overhang, but in a pleasant, musically consonant way." AD was also impressed by the Black's bass: "The lowest notes had plenty of power and reach and a slightly frightening physicality," he wrote, ascribing this to the Jadis's hand-wound output transformers. In his measurements, JA found that the Black had an unusually high output impedance—3.5 ohms—and that it only met its specified power of 40W at higher levels of distortion than our usual 1%. The Jadis should not be partnered with loudspeakers whose impedance drops below 4 ohms, JA concluded. Nevertheless, "very strongly recommended" was how AD summed up his auditioning. (Vol.43 No.4 WWW)

Krell K-300i: $9500 with DAC option, without DAC $8500
From the company whose name was at one time synonymous with class-A solid state amplification comes this 150Wpc class-AB integrated—yet the K-300i's sliding-bias scheme, called iBias, allows it to run in class-A all the way up to 90Wpc, according to the manufacturer. An optional DAC ($1000) decodes PCM to 24/192 and, via USB, DSD to 128, and works with the ConversDigital mConnect app, which also allows streaming from Tidal, Qobuz, et al. In auditioning the Krell, JVS noted neutral timbres with "just a touch of inviting warmth" and fine spatial dimensionality, observing that, of the integrateds he has reviewed, the K-300i is the standout. Technical Editor JA noted that the Krell has "just sufficient heatsinking for its power rating" (it shut itself down while undergoing preconditioning), and excessive digital-input gain, the latter associated with the introduction of low-level spuriae, but was pleased that the K-300i exceeded its rated output power (190 instead of 150Wpc). "Overall … excellent measured performance," he concluded. (Vol.42 No.12 WWW)

Linear Tube Audio Z10e: $6950
See Headphones & Headphone Accessories (Vol.43 No.5 WWW)

Luxman L-509x: $9995
Integrated amplifiers with tone controls—not to mention switch-selectable outputs for two pairs of speakers, power-output meters, a balance control, a tape monitor button, and a built-in phono stage with MM and MC inputs—are rare beasts. And with its rated power output of 120Wpc into 8 ohms—not to mention its weight of nearly 65lb—the solid state Luxman L-509X is indeed a beast, and one whose subtly retro styling impressed KM, who called it "a behemoth of beauty." Ken was also taken with the Lux's sound: "Record after record, the L-509X illuminated every important aspect and area of the recording. It lived and breathed in the air around the notes, consistently creating big, solid, spatially natural images." And even though KM never really warmed to using its tone controls—though he admired the "very smooth, finely graded" adjustments they provided—he concluded that the L-509X was "one of the most intimate-sounding, dynamic, texturally nuanced, truthful purveyors of music of my experience." Writing from his lab, JA found that the L-509X "comfortably exceeded" its output-power specs, and declared the amp "a conservatively engineered design, with low noise and distortion and an excellent phono stage." (Vol.41 No.5 WWW)

Marantz Model 30: $2999 $$$
This elegant-looking amplifier's output stage uses Hypex NC500 class-D modules and is specified at 100Wpc into 8 ohms or 200Wpc into 4 ohms. JA's measurements indicated the Model 30 significantly exceeded those powers, clipping at 165Wpc into 8 ohms and 240Wpc into 4 ohms. Not always a fan of class-D amplifiers, HR wrote that "the Marantz version of class-D clarity brought greater transparency to the upper five octaves, in a way I have not previously experienced with any class-D module." Compared with the more expensive Yamaha A-S3200, HR felt that while the Yamaha represented "bright-n-ready, old-school, class-AB vivo," the Marantz sounded darker, less extraverted, with "more silence in the silences and more space in the soundspaces." He also found that the Marantz partnered well with Magnepan .7 speakers, pulling out "shovelsful of previously hidden subtleties." The Model 30's headphone output will work better with high-impedance 'phones. No digital inputs, but the Marantz has a versatile, low-noise, low-distortion phono stage that offers a moving magnet mode and three moving coil modes, labeled MC Low, MC Mid, and MC High, and different combinations of gain and resistive loading. (Marantz also offers a matching SACD player/streaming DAC, the SACD 30n.) HR summed up his auditioning, "The Marantz Model 30 integrated suits my taste for simple sophistication. Its phono stage is … versatile and musically effective. … Best of all, this stylish new Marantz is a well-tuned, supertransparent, superdetailed class-D amplifier that powered diverse loudspeakers with a captivating élan worthy of its 'Model 30' heritage." (Vol.44 No.1 WWW)

Mark Levinson No5805: $9300
"It's the feature set that impresses most" said JCA of the new Levinson integrated—not a surprising point of view considering the No5805's MM and MC phono inputs; digital inputs that accept PCM to 32/284 and DSD up to DSD256; a headphone amplifier; and support for Bluetooth wireless (but not from iPhones) and full MQA decoding and rendering. JCA noted that the Levinson delivered sonic images that were larger in size, closer in spatial perspective, and "perhaps slightly more vivid" but also "marginally less live-sounding" than his more expensive reference amplification chain and DAC. But ultimately, when shifting from critical listening to simple enjoyment, JCA found the No5805 to be "captivating, distracting. … Paired with the excellent Revel Ultima2 Salon2 loudspeakers, the Levinson made enchanting music." Noting that the class-AB No5805 exceeded its power specs (133.5Wpc instead of 125Wpc), Technical Editor JA praised its "excellent measured performance." (Vol.42 No.7 WWW)

McIntosh MAC7200: $7500
This classic stereo receiver may well be the most expensive model currently available, but LG was mightily impressed by what it offers. In addition to McIntosh's traditional blue level meters and an excellent FM stage, it offers S/PDIF and USB digital inputs, line and MC/MM phono analog inputs, and a headphone output. (JA's measurements suggest that the latter will work best with high-impedance cans.) The transformer-coupled, solid state output stage offers a maximum power of "at least" 200Wpc into 2, 4, or 8 ohms; JA measured 255Wpc into 8 ohms, 235Wpc into 4 ohms, and 283W into 2 ohms from the respective output-transformer taps. LG found that the MAC7200's tuner equaled his Day Sequerra FM Reference's ability to generate a jet-black background and render broadcast music punchy, dynamic, and involving, although it lacked the FM Reference's transparency and selectable bandwidth filters. "The FM tuner is this product's jewel," he wrote, adding, "its sensitivity, selectivity, and ability to quiet with an FM signal equaled and in many cases bettered my FM Reference tuner." Auditioning the MC phono input, LG noted that it rendered a favorite LP with stunning transients, wide soundstage, and incredible detail, easily besting the CD version of the same work. He also liked what he heard from the Mac's digital inputs, commenting that they matched his reference Bryston DAC's dynamics, background quietness, and depiction of the soundstage. Summing up, LG wrote that the MAC7200's power, resolution, dynamics, and transparency are among the best he has heard: "If you have the sturdy shelf space for its large, heavy chassis, are a fan of FM radio, and are looking for one unit to handle many different two-channel tasks, the MAC7200 should be on your short list." (Vol.44 No.1 WWW)

Moonriver 404 Reference: $4995
As supplied for review, this Swedish amplifier included optional digital and MM/MC phono analog inputs. The digital module, though, was based on an AKM DAC chip that is no longer available following the disastrous fire at the Japanese manufacturer's factory, so the review didn't discuss the digital input. But with the single-ended line inputs, JVS wrote that while the sense of air wasn't as breathtaking as through his expensive reference amplifier, "the music sounded airier and more colorful and seemed to emerge from a quieter background" than what he'd recently heard through the two more expensive integrateds. "Plenty of bass showed that the low-powered Moonriver 404 Reference has what it takes to drive the challenging Wilson Alexia 2's," he added. Summing up, JVS wrote that the Moonriver 404 Reference "does justice to complex and demanding recordings. It sounds tonally spot on, well balanced, clear, and musical." Although the 404 Reference uses an output stage based on Texas Instruments' LM3886 chip, which is specified as being able to deliver 50W into 8 ohms and 70W into 4 ohms, JA found that the Moonriver clipped at 39.5Wpc into 8 ohms and 60W into 4 ohms. Although the Moonriver has single-ended preamplifier outputs, JVS found that these "buzzed" with his reference monoblocks, and JA found that there was a high level of ultrasonic noise on the preamplifier outputs. (This may have been a sample fault.) In his measurements, JA also noted low-level power-supply spuriae and that the distortion signature was primarily the subjectively benign second harmonic. Intermodulation distortion was not excessive. (Vol.44 No.2 WWW)

NAD Masters Series M33: $5499
This extraordinarily versatile amplifier incorporates a fully integrated BluOS streaming platform, sophisticated control options, Dirac room correction, analog line and MM/MC phono inputs, digital inputs, a headphone output, and an output stage based on the Purifi Eigentakt class-D technology developed by Bruno Putzeys. KR was impressed. Listening to a brass band recording, he found the M33's sound notably transparent. "There was a satisfying balance between the drum and tuba at the low end, the brashness of the upper brass, and the filigree of winds in between," he wrote, going on to say that "the soundstage was full and wide, and there was the impression of significant weight and body." "The M33, in one well-integrated and handsome box, replaces all the traditional components and can be operated from a smartphone or a tablet," concluded KR, adding "Keep your beloved speakers and let the NAD M33 do everything else. It will do it all superbly." On the test bench the M33 exceeded its specified continuous output power of 210Wpc into 8 ohms and delivered 460Wpc into 4 ohms. JA was impressed by the "excellent" phono stage and concluded that "NAD's M33 packs a lot of well-engineered performance into its relatively small chassis." The M33 was both Stereophile's Amplification Component of 2020 and the magazine's overall Product of 2020. (Vol.43 No.10 WWW)

Pass Laboratories INT-25: $7600 $$$
To HR, who prefers integrateds over separates yet wouldn't even consider buying an amp with a built-in DAC—"Why would I pollute a fine audio component with a non-upgradable and possibly third-rate ancillary?"—the Pass INT-25 emerged as an ideal component. The remarkably heavy (51lb) INT-25 is essentially a Pass XA25 power amp—class-A push-pull without degenerative feedback and offering 25Wpc—wedded to a minimalist line-level preamp. Used with his DeVore O/93 speakers and playing Erich Leinsdorf's recording of Wagner's Die Walküre, Herb found that "the INT-25 let the O/93s make that Die Walküre into something so beautiful I just laid back and basked in it." He also felt the INT-25 is capable of putting across "a subtle radiance" that eludes other solid state electronics. With the amp on his test bench, JA found "much to admire in the Pass Labs INT-25's measured performance." HR's last word: "my new solid state reference." (Vol.43 No.2 WWW)

Riviera Audio Laboratories Levante: $16,500
This hybrid, analog-input–only, Italian design features tubed front-end circuitry and a MOSFET output stage that can be operated in class-A, in which it offers a maximum power of 30Wpc into 8 ohms, or class-AB, in which it offers 120Wpc into 8 ohms. (JA had to relax our definition of clipping to 3% THD+noise for the Levante to meet its specified powers.) There is no global loop negative feedback because the designer believes this causes the distortion signature to mimic that of human hearing. JA found that distortion at moderate powers was close to 0.5%, though this was almost entirely the subjectively innocuous second harmonic. HR's first impression was that the Levante, fitted with vintage Mullard input tubes, sounded "Too lush. Too big. Too densely atmospheric." The review sample was supplied with modern JJ tubes as well as the Mullards. Changing to the stock JJ tubes produced a sound that was more overtly direct, less misty and possessed of a more sharply focused, less-granular clarity than with the Mullards. Other than the increase in power, HR didn't notice much difference between class-A and class-AB operation. The Levante's headphone output had a moderately low source impedance of 18 ohms. While HR found the low-sensitivity, 60 ohm HiFiMan Susvaras sounded slightly rounded off, the sound with the sensitive, 300 ohm ZMF Vérité closed-backs was "unusually precise and vibrant." "I never imagined there'd be an integrated amplifier with a headphone amplifier of this caliber," he concluded. (Vol.45 No.2 WWW)

T+A PA 3100 HV: $24,500
This powerful solid state integrated amplifier offers up to 300Wpc into 8 ohms and 500Wpc into 4 ohms—JA measured clipping powers of 318Wpc/8 ohms and 525Wpc/4 ohms. JA also noted that while distortion was not especially low—though it remained below 0.1% at high powers into loads >2 ohms—it was commendably consistent with frequency and consisted primarily of the subjectively innocuous second harmonic. The PA 3100 HV has both balanced and unbalanced inputs and preamplifier and headphone outputs—the latter best suited for high-impedance headphones—as well as the usual loudspeaker outputs. The review sample was not fitted with the optional Tone Control/Room Correction ($2900) or MM/MC phono input ($1600) modules, nor was it supplied with T+A's PS 3000 external power supply ($14,500). Nevertheless, JVS found that this amplifier's "consistently musical presentation" emphasized "smoothness and ease over strong contrasts and abrupt shifts" and described it as "a powerful transmitter of musical truth." He summed up the PA 3100 HV as "an excellent, meticulously engineered, beautifully made integrated amplifier." (Vol.44 No.4 WWW)

Technics SU-R1000: $9499
This groundbreaking "digital" amplifier offers MM and MC phono, line-level, and digital inputs and maximum powers of 150Wpc into 8 ohms and 300Wpc into 4 ohms. (JA's measurements indicated slightly higher clipping powers into both loads.) The SU-R1000 makes extensive use of DSP: "JENO" (Jitter Elimination and Noise-shaping Optimization) eliminates jitter during the conversion of all signal to high–sample-rate PWM to drive the output transistors; "Load Adaptive Phase Calibration" measures the output gain and impedance phase characteristics of the amplifier and speaker to create an ideal impulse response; "Active Distortion Cancellation Technology" compensates for the back electromotive force produced by speakers; and "Intelligent Phono EQ," which optimizes the RIAA equalization and channel separation. (A test LP is included to allow this last feature to be implemented for the user's specific phono cartridge. JA found that even without the Intelligent Phono EQ, the SU-R1000's RIAA correction was extraordinarily accurate—one of the best he has ever measured.) "The Technics SU-R1000 is not a class-D amp 'on steroids,' and it's not a solid state amp emulating a tube amp," wrote KM. "It's unlike any amplifier I've heard. The SU-R1000 achieved levels of performance and sound quality I've not previously heard from any amplifier, except in terms of tone and texture." (KM preferred his reference tube amplifiers for these qualities.) "The SU-R1000 may be technically complex, but its sound was simple, whole, and true with exceptional transparency, flow, and imaging … warm and a touch rich," he decided. JA concluded that the Technics SU-R1000 line-level analog inputs, phono inputs, and digital inputs all offered excellent measured performance. (Vol.44 No.12, Vol.45 No.1 WWW)

Yamaha A-S3200: $7999.95
The styling of this well-finished, hot-running integrated amplifier evokes memories of the Japanese company's "Natural Sound" receivers from the 1970s. The A-S3200 offers both balanced and singled-ended line inputs, headphone, preamplifier, and loudspeaker outputs, and tone controls. JVS liked the headphone outputs, commenting that "the welcome smoothness and beauty of the presentation, and … the excellent left-right soundstaging, earn the headphone amp a big thumbs up." However, he was less happy with the A-S3200 driving his Wilson Alexia 2 loudspeakers, writing that while "air and depth were pretty good, the soundstage was as wide as I've come to expect from other integrated amplifiers I've evaluated, and musicality was a constant," what stood out most was "a predominant midrange whose color palette, compared to my reference, seemed somewhat restricted." JVS suspected that the Yamaha was not an optimal match for his current-hungry Wilson speakers, mandating a Follow-Up with higher-impedance loudspeakers. In that Follow-Up, HR found that the A-S3200 played more dramatically into Harbeth 30.2 speakers than his reference Pass Labs INT-25 had. "Bass had more force and bite," he wrote and concluded that "this luminous, retro-looking integrated is more than a babyboomer nostalgia toy. It is a serious, high-value music-playing machine." On the test bench, the A-S3200 exceeded its specified maximum continuous power of 100Wpc into 8 ohms and 150Wpc into 4 ohms, clipping at 110Wpc and 168Wpc, respectively. Line-input gain was on the high side, though the MM- and MC-capable phono input offered appropriate gains for both types of cartridge. (Low-output MC types will probably better match this input.) RIAA equalization featured slight boosts in the treble and midbass regions; the phono input's distortion and noise were very low. HR's Follow-Up included an audition of the A-S3200's phono stage. Using a Koetsu cartridge loaded at 50 ohms, the Yamaha "played instruments with exceptionally tight bass and a detail-packed midrange." HR concluded that "Overall, the Yamaha's phono stage far exceeded my expectations," though he warned that those who utilize the A-S3200's phono stage will need to choose MC cartridges with care. Even so, he added that he was certain that no one would be disappointed with the moving magnet input. (Vol.43 Nos.9 & 11 WWW)

B

Aesthetix MIMAS: $7500 plus options
Aesthetix Audio's first integrated amplifier, the Mimas mixes a fully differential tubed preamp with a balanced, zero-feedback, DC-coupled (servo-less, accomplished by means of careful parts selection), solid state output section in a 44lb package. Features include Aesthetix's own in-house-wound mains transformer and a fully balanced volume control constructed with 60 individual resistors, providing volume increments of 1dB each. Extra-cost options, not reviewed, include a phono card, a DAC card, and an Ethernet card. JVS praised the Mimas's "gratifyingly neutral … sound whose beauty extended through its excellent bass, convincing pace and drive, and delightful touch of radiance," while noting that it exhibited less transparency and inter-note silence than the best amplification chains he has used: "As Schubert's music tugged at my heart, I noted the lovely liquid ringing of the piano's high notes and the beauty of the sound overall," he wrote. "But the music lacked transparency and the space between notes was less silent than I'm used to." Writing from his test bench, JA observed that the Mimas is "generally well engineered." (Vol.42 No.8 WWW)

Bryston B135³: $6995 as reviewed
The only integrated amplifier Bryston makes, the B135³ combines their BP-17³ preamplifier and 2.5B³ amplifier in one box, available in 17" or 19" versions. An optional DAC card adds $750 to the base price. For another $1000, the Aux 1 input becomes a moving magnet phono input. Writing about the basic amplifier, HR concluded that it "sounds like it looks: understated, recording-studio quiet, detailed, easy-flowing, low-distortion, tone-correct, and low-fatigue. The B135³ always plays music engagingly." The Bryston is specified as offering maximum powers of 135Wpc into 8 ohms and 180Wpc into 4 ohms; JA's measurements indicated that it exceeded those powers, clipping at 155Wpc into 8 ohms and 230Wpc into 4 ohms. HR noted that with his low-impedance headphones, the Bryston's headphone output sounded "rolled-off and unsparkly." JA found that the headphone output impedance was a relatively high 71 ohms, which means that the Bryston will be better suited to high-impedance headphones, like Sennheisers. JA wrote that the B135³ offered extremely low levels of distortion, though he advised that "background noise will be at its lowest when the volume control is below the maximum." (Vol.44 No.12 WWW)

Cambridge Audio CXA81: $1299 $$$
The CXA81 is a versatile, solid state integrated amplifier with analog and digital inputs, headphone, preamplifier, and subwoofer outputs, and the usual loudspeaker outputs. JA found that the Cambridge slightly exceeded its rated power of 80Wpc into 8 ohms and 120Wpc into 4 ohms. Using its line inputs, the CXA81 had KM muttering "wow" (several times) at its transparency to the sound of upstream electronics and recordings. Using both Polk and Quad loudspeakers, the amplifier "consistently created a large, atmospheric soundstage with solid images." The Cambridge's digital inputs were consistently satisfying, though not in the class of KM's reference BorderPatrol DAC, which costs 50% more than this DAC-equipped integrated amp. Compared with the more expensive, "fully loaded" Schiit Ragnarok 2, the CXA81 had better top-end air, a slightly wider and deeper soundstage, and a more laid-back presentation; the Schiit amp offered better tone, slightly better drive, and more intimacy. The CXA81 helped KM realize "how much music can be had for such a low price. It knocked me flat with its ability to sound good in so many ways." (Vol.44 No.1 WWW)

Cambridge Audio EVO 150: $3000
The Roon-Ready, "all-in-one" EVO 150 has digital, line, and MM phono inputs, can stream audio via a network or Bluetooth connection, and can unfold MQA-encoded data. It "continues Cambridge's tradition of offering near-cutting-edge products that don't break the bank," RS wrote. He was impressed by what he heard, finding that the Cambridge sounded "fresh-faced and convivial, with a dynamic spring in its step. There was a confident, unforced quality that let the music unfold gracefully," adding that the amplifier maintained its composure at high volume. JA found that the class-D EVO 150 met its specified maximum power into 8 ohms (150Wpc) and delivered 280Wpc into 4 ohms before clipping. "With the exception of the higher-than-expected levels of noise in its headphone output, the Cambridge EVO 150's measured performance reveals excellent audio engineering," JA summed up. RS was equally impressed, concluding that everything about the EVO 150—its ergonomics, features, streaming app, remote, and, most essentially, sound quality—operated at a high standard. (Vol.44 No.10 WWW)

Cary Audio SLI-100: $5995
A push-pull tubed integrated amp that uses two KT150 pentode tubes per side, operating in Ultralinear mode, to output 100Wpc, the SLI-100 provides the user with four line-level inputs, all unbalanced, and a choice of 8 or 4 ohm output taps. The output section is biased for class-AB and employs 4dB of negative feedback. In addition to the four output pentodes, the Cary uses four small-signal tubes—two 6922s, two 6SN7s—and splits the signal phase with a cathodyne ("split-load") phase inverter, for which HR expressed preference when compared with the more common long-tailed pair/dual-differential stages. Also integral to the design is a voltage-gain stage constructed with shunt-regulated push-pull architecture, also a Herb favorite. This all added up to an amplifier that allowed violinist Joseph Szigeti, playing Bartók, to wring the most "tearjerking presence and texture" from HR's Harbeth M30.2 loudspeakers. In measuring the SLI-100, JA found "a slight degree of overshoot" in the amp's squarewave reproduction and, far worse, strikingly less output power/higher distortion than specified: "I was disappointed in the Cary Audio SLI-100's measured performance." (Vol.41 No.12 WWW)

Cary Audio SLI-80HS: $4495
This most recent version of Cary's longstanding SLI-80 vacuum tube integrated amplifier—the HS stands for Heritage Series—departs from its forebears with a solid state–rectified power supply and switch-selectable output architectures: Given an 8 ohm load, its KT88 tetrode tubes can generate 40Wpc in triode mode or 80Wpc in Ultralinear mode. The Cary offers three line-level inputs (there is no phono section), switch-selectable 4 ohm and 8 ohm outputs, and a front-mounted headphone jack. KM found the SLI-80HS to be less "syrupy" than Cary amps of yore, describing the new amp as "a truth-teller, with few opinions of its own," and praised in particular its bottom-end extension. JA's measurements revealed output power that was less than the manufacturer's specs. He noted that Ultralinear operation offers "the lowest midrange distortion and the highest power, at the expense of a higher output impedance than triode mode." (Vol.42 No.11 WWW)

Exposure XM5: $1895
The Exposure XM5 blends retro and cutting-edge with apparent ease, combining an MM-friendly phono stage with a 24/192 USB DAC in a case whose half-width size calls to mind the pre-1993 Naim Nait. A class-AB output stage uses complementary pairs of bipolar transistors to deliver 60Wpc; speaker connectors are banana-only. AD praised the XM5 for its freedom from upper-frequency etch and found its phono performance, though temporally precise, a bit dull: "CD playback, through its line stage, was more colorful and vibrant," he said. Writing from his test bench, JA observed that the hot-running XM5 had insufficient heatsinks "for sustained operation at highish powers" but exceeded its power spec, providing 70Wpc into 8 ohms. His verdict: "generally good measured performance considering its affordable price," though he was less impressed by the performance of its digital inputs. (Vol.42 No.6 WWW)

Line Magnetic LM-845IA: $4950
Replacing HR's long-term reference tube amplifier, the LM-518IA, the Chinese LM-845IA weighs a back-breaking 77lb and still uses a single hot-running 845 tube for each channel's output, but has internal component changes and redesigned output transformers, these sourced from Japan. It also uses 12AX7 input tubes, a 5AR4 rectifier, and a pair of triode-operated 6P3P beam tetrodes to drive the grids of what AH described as "those slightly terrifying 845s." The Line Magnetic offers 4, 8, and 16 ohm speaker terminals, three line-level inputs, and a preamplifier input for those wishing to use the LM-845IA as a power amplifier. A nicely machined aluminum remote with volume and mute buttons is included. What AH noticed first in his auditioning were "the hallmarks of a well-designed single-ended triode (SET) amplifier: a bell-like clarity, lots of textural information, and a distinctive three-dimensionality to the sonic images. … With the Line Magnetic and the 16 ohm taps, the soundstage was expansive in width, height, and depth, with instruments and voices floating free of and well above my Altec Valencia 846A speakers." The LM-845IA's maximum power is specified as 22W. JA found that with our usual definition of clipping, which is when the output's THD+noise percentage reaches 1%, with both channels driven with a 1kHz signal the LM-845IA's 16 ohm tap clipped at just 2Wpc into 16 ohms, though it did offer the specified 22W from this tap at 3.5% THD+N. Unusually, the Line Magnetic's 16 ohm and 8 ohm output transformer taps worked best with impedances that were lower than the nominal tap value. However, these two taps have sufficiently high output impedances that the LM-845IA's sonic character will be different with every loudspeaker with which it is used. The 4 ohm tap has a lower output impedance, JA noted, but this is at the expense of higher distortion, even at low powers, than the higher-impedance taps. He did find, however, that the LM-845IA was significantly quieter than its predecessor. Class B rating reflects high output impedance, which means performance will depend on the loudspeaker used. (Vol.44 No.7 WWW)

Luxman SQ-N150: $3295
A part of Luxman's newly revived NeoClassico series, the SQ-N150 is built around a 10Wpc (into 6 ohms) tubed output stage that uses stereo pairs of EL84 output pentodes preceded by two 12AX7 dual-triodes. (The EL84s run in fixed-bias mode, but adjustments cannot be made from outside the casework.) The chunkily compact Luxman also includes tone controls, a headphone amp, and a moving magnet/moving coil phono stage and is supplied with a metal-enclosed remote—and we haven't even mentioned the classic good looks of its VU-meter–enhanced control panel. KM described the little Lux as "one of the most transparent components I've had in my system," with a "sweet" tonality and the ability to throw a wide, deep soundstage. In measuring the SQ-N150, JA found evidence of "well-designed" output transformers and an output of 12.5Wpc into 8 ohms. His conclusion: "It is well-engineered and offers excellent measured performance within its limited power envelope." (Vol.42 No.12, Vol.43 No.1 WWW)

Musical Fidelity M8xi: $6999
This hefty (101lb), powerful amplifier—JA measured clipping powers of 500Wpc into 8 ohms, 650Wpc into 4 ohms—offers both analog and S/PDIF and USB digital inputs. When JVS switched from his almost six-times-as-expensive reference monoblocks, he found the M8xi's sound via its balanced analog inputs "virtually as pleasing, and spot-on neutral, albeit less transparent and airy and less precise in its depiction of acoustic space." Playing his favorite extreme-bass test track, "Electrified II" by Yello, with his demanding Wilson Alexia 2 speakers, he wrote that "even if [the Musical Fidelity's] bass wasn't as gut-shaking—even if the soundstage didn't seem to reach out to me and gobble me up body and soul—it sounded really good." Turning to the M8xi's digital inputs, JVS felt that these bettered those in the Krell K-300i. He summed up the Musical Fidelity by writing that not only was it the most powerful and least expensive of the seven integrated amplifiers he has reviewed in recent years, it was also one of the best-sounding. (Vol.43 No.10 WWW)

NAD M10 V2: $2749 $$$
The words integrated amplifier are scarcely adequate to this task: The compact (only 8.5" wide) NAD M10 incorporates the BluOS operating system/music playback app; network, Wi-Fi, and Bluetooth connectivity; analog and digital inputs; support for Tidal, Qobuz, et al.; multiroom capabilities; Dirac Live LE room correction (one hopes not the Delbert Grady sort); and a big "Gorilla Glass" display on its front panel—all this plus a 100Wpc class-D (nCore) amplifier. As for that last bit, JA expressed surprise at how good the NAD sounded, even when compared to a pair of monoblocks with a five-figure price tag. (The NAD actually offered better note definition, if not quite the same degree of deep bass extension and authority.) JA-the-listener concluded that the NAD "offers everything serious audiophiles and music lovers need to enjoy their music," while JA-the-measurer noted that "NAD's M10 packs a lot of well-engineered performance into its relatively small chassis." (Vol.43 No.1 WWW)

Naim Audio Uniti Nova: $6899 ★
The star of Naim's rebooted Uniti line, the Nova combines an 80Wpc integrated amplifier with a media player and streamer, the latter supporting Tidal and Spotify. The Nova offers Bluetooth aptX HD and Wi-Fi connectivity, and provides vTuner Internet radio as well as support for most music-file types, up to 384k PCM and DSD128. All user controls are accessible via an included remote control, Naim's downloadable app, and a full-color front-panel LCD display that KM described as "lovely," supplemented with a top-panel rotary control. Ken was enchanted with the Uniti Nova's radio function, and found its file-playing capabilities ergonomically comforting—"I was surprised by the Nova's ease of setup and practically instantaneous response"—and sonically rewarding: "file after file drove my jaw floorward as my ears reveled in the Nova's beautiful sound." KM's verdict: "the Uniti Nova is practically a bargain. Definitely, effusively, highly recommended." Apart from noting some anomalous behavior with 96 and 192kHz data—their responses were down by 9dB at the ultrasonic frequency of 29kHz—JA wrote from his test bench that "the Naim Uniti Nova's measured performance reveals it to be well sorted, as they say in the UK." (Vol.41 No.3 WWW)

Outlaw Audio RR2160MkII: $999 ★ $$$
The RR2160—or, as Outlaw Audio calls it, their "Retro Receiver"—marries a 110Wpc class-AB integrated amplifier to an FM/AM tuner of the traditional sort, along with an MM/MC phono stage. Its tone controls—yes, tone controls!—and bass-emphasis switch hark back to an era of mustaches, flared trousers, and loudspeakers with sculpted-foam grilles, yet the RR2160 doesn't skimp on modern conveniences, including Ethernet connectivity, HD radio, an MP3 input, a headphone amp with independent volume controls, and a 24/192 DAC with USB, coaxial, and optical inputs. After being broken in and warmed up, the Outlaw rewarded HR with "a generously big, warm, articulate sound." Used with a CD transport, the RR2160's Burr-Brown–based DAC didn't reach the same performance heights as more expensive outboard processors, yet nonetheless surprised Herb with its "unfettered verity." The Outlaw's MM phono inputs performed well when addressed with a good-quality step-up transformer, though HR was disappointed by the lack of adjustability in its MC inputs. And its headphone section "far exceeded" HR's expectations. Writing from his test bench, JA noted the Outlaw's "significantly" higher-than-specified output power, the admirably low output impedance of its headphone amp, and its "superb" phono stage, though he was "somewhat disappointed by the measured performance of its digital inputs." HR's conclusion: "a conspicuously good-sounding audiophile product at a ridiculously low price." New version keeps performance the same but eliminates AM radio and adds Wi-Fi. (Vol.40 No.12 WWW)

Parasound Halo Hint 6: $2999 ★
Introduced in 2014, Parasound's Halo integrated amp offered 160Wpc from its bipolar output section—JFETs and MOSFETs were pressed into service elsewhere in the amp—plus a list of convenience features including a dedicated subwoofer output with its own variable high- and low-pass crossover filters; a 32-bit DAC with USB, coaxial, and optical inputs; a discrete headphone amplifier; an MM/MC phono stage; and a total of six line inputs (one balanced, five unbalanced). That amp has now been replaced by a refined version, the Halo Hint 6, with improvements that include a Burr-Brown electronically controlled analog volume control; a plug-and-play USB receiver; an increase in gain for its MM phono stage; and a bump-up in output power, to 180Wpc. KM tried the Hint 6 with a variety of speakers, commenting on the amp's sonic "wholeness and refinement," and for bringing "control and nuance" to his DeVore O/93s. His conclusion: "The Hint 6 worked well with every speaker I threw at it, delivering an upfront, slightly cool, dynamic sound. Recommended." (Vol.38 No.11, Vol.42 No.5 WWW)

Quad Artera Solus Play: $2495
Here's another of those products that stretches if not quite smashes the category for integrated amplifiers: The Artera Solus starts with a 75Wpc class-AB amplifier, with a headphone jack and two line-level inputs, and adds to that a D/A processor with multiple inputs—via USB it does 32/384 PCM and DSD256—and a front-loading CD player, all in a more-attractive-than-usual enclosure. Streaming Tidal and Qobuz files through the Quad's USB input, HR heard "a greater sense of force and density" than with his reference standalone DAC, but it was the CD player that Herb concluded was "the Artera Solus's raison d'être," noting that, "In my house, streaming usually sounds better than CD—but not with the Artera Solus." That said, HR didn't consider the headphone output good enough for "serious headphone enthusiasts." The verdict from chief tester JA: "[The Quad is] well-sorted, as they say in the UK." (Vol.43 No.3 WWW)

RAAL-requisite HSA-1b: $4500
See Headphones & Headphone Accessories (Vol.44 No.10 WWW)

Rogue Audio Sphinx V3: $1595
Descended from the original Sphinx that HR reviewed in 2014, the V3 is still "an old-school, 25lb, made-in-America integrated amplifier with three line-level inputs … and a 12AU7-based, mu-follower preamplifier stage driving a 100Wpc (into 8 ohm), class-D, solid state power amplifier." The phono stage now has adjustable loading and gain so it can be used with both MM and MC cartridges. (The RIAA correction incorporates the IEC-recommended low-frequency rolloff, reaching –3dB at 30Hz.) Headphone output is now based on discrete MOSFET devices, which JA found led to a very low source impedance, appropriate even for low-impedance cans. With CDs, HR found that the Sphinx V3 "delivered a good amount of leading-edge bite and trailing-edge flow. Bass felt quicker and more articulate. The V3 displayed a fun, taut energy the original did not have." He tried the phono input with the Ortofon 2M Black moving magnet and Hana EL moving coil cartridges and concluded that "The Sphinx V3's MM/MC phono input did proclaim the virtues of analog." HR summed up the V3's headphone amp as "not as powerful, dynamic, or transparent as the Schiit Ragnarok's, but it's closer to that than any others I've auditioned." Overall, he summed up the Sphinx V3 as "an unpretentious working-person's amplifier. It delivers music with an eager expressive energy, in concert with a forgiving musical nature." On the test bench, the V3 didn't quite meet its specified power, clipping at 96Wpc into 8 ohms, and the phono stage's RIAA equalization was slightly mismatched between the channels, with the right channel up to 0.9dB higher in level in the treble than the left. (Vol.43 No.8 WWW)

Schiit Audio Ragnarok 2: $1799
The first example of Schiit Audio's new Nexus current-feedback amplifier technology, the Ragnarok 2 improves on the original in a number of ways. As just an integrated amp, without add-ons—in which guise the Rag 2 sells for less than the cost of its predecessor—the redesigned amp also adds an improved volume-control circuit and remote handset. The Rag 2 is also available "Fully Loaded" ($1799), with an MM phono stage and a USB DAC. That's the version KM tried, and while listening to Ella Fitzgerald on vinyl he found that "vocals sounded more human and less canned than I've ever heard"—and with other LPs, drum thwacks "revealed an amplifier that doesn't soften transients." JA found higher-than-specified output power into 8 ohms—78Wpc instead of 60—but slightly less than the specified 100Wpc into 4 ohms, ultimately declaring the amp "well-engineered" and the phono stage "excellent." JA says: Class C for the digital input. (Vol.43 No.2 WWW)

VAC Sigma 170i iQ: $10,000
American-made, well-finished integrated amplifier uses KT88 output tubes in autobiased Ultralinear, push-pull configuration with 2–4, 4–8, and 8–16 ohm output transformer taps. (These are wired in inverted polarity.) Preamplifier stage and optional MM/MC phono stage use 12AX7s. JMu felt that the VAC 170i iQ's sound quality featured a sweet treble, excellent midrange, musicality, and bloom and commented that timbres were more natural than warm, and that bass was substantial, with good definition. "The VAC amp seemed more powerful than its rating suggests, and often delivered solid attacks," she concluded. The Sigma 170i iQ's maximum power is specified as 85Wpc into 4, 8, or 16 ohms. However, on JA's test bench, the VAC amplifier delivered 11.8Wpc into 8 ohms at 1% THD+N and 51Wpc into 8 ohms at 3% THD+N from the 8–16 ohm output transformer tap. Higher powers were available from the 4–8 ohm tap—32.6Wpc into 8 ohms (1% THD+N) and 79Wpc (3% THD+N). The 2–4 ohm tap was probably optimal for real loudspeaker loads, felt JA, as it reached 3% THD+N at 53Wpc into 8 ohms and 75Wpc into 4 ohms. However, the Sigma 170iQ's output impedance was high, especially from the 8–16 ohm tap, meaning that its sound quality will be different with every loudspeaker it is used to drive. Phono input features accurate RIAA equalization, but low overload margins at low frequencies mean that low-output phono cartridges will work better with this input. (Vol.44 No.4 WWW)

Vincent SV-737: $3499.95
Designed in Germany and made in China, this relatively affordable but versatile integrated combines a tubed input stage with an output stage biased to deliver the first 10W of the maximum 8 ohm power of 180W in class-A. The single AEG 85A2 tube that peers out from the faceplate window is a professional gas stabilizer tube, an integral part of the high-voltage power supply regulation for the preamplifier. The preamplifier stage uses two 6N1P and two 6N2P tubes, offers tone controls, and is fed signal by six pairs of single-ended line inputs. Another pair of single-ended inputs feeds the power amplifier stage directly. Digital inputs include three S/PDIF (one optical, two coaxial), Wi-Fi, and Bluetooth. As well as speaker outputs, the Vincent has preamplifier and headphone outputs. "Out of the box, the Vincent wowed with crisp transients, detailed treble, neutral upper mids, rich, lush lower midrange, and powerful bass," wrote KM. While he found the amplifier largely transparent from the mids up, the Vincent "added a pleasing extra dollop of energy, warmth, and color down low." He liked the sound of the S/PDIF digital inputs, which produced "gobs of air, refined, corporeal images, and a deeper soundstage" compared with his reference Tascam CD player. JA found much to admire in the amplifier's measured performance, though he felt that the digital inputs and headphone output should be regarded as more for convenience than for absolute performance. He also found that the SV-737 didn't quite meet its specified power, delivering 155Wpc into 8 ohms and 240W into 4 ohms at 1% THD+N with both channels driven. However, it appeared that one of the review sample's left-channel tubes was starting to fail; while the right channel offered very low levels of distortion, the left channel's THD was almost 20 times higher, at 0.1% across the band. (Vol.44 No.7 WWW)

C

NAD C 328: $649 $$$
The budget-priced NAD C 328 combines Bluetooth connectivity, a 24-bit/192kHz DAC based on a Cirrus Logic chip, an MM-ready phono stage, and a Hypex-based class-D amplifier rated at 40Wpc into 8 ohms—all in an enclosure whose size and appearance are closer to those of the company's legacy products than this amp's contemporary stablemate, the odd-looking D 3020. Cynical readers might expect less than the best sound from such a humble thing—and indeed, during his time with the C 328, KM found a few recordings that coaxed from it a bit of treble harshness, and a few others that lost a bit of flesh and blood on their trip through the NAD. But when mated with the right speakers—KM got the best results with Elac's Debut B6 ($279/pair)—this amp "consistently made music with a detailed, very dynamic, natural sound." In measuring the NAD's amplifier section, JA uncovered a superbly high signal/noise ratio, higher-than-specified output power, and very low distortion, with similarly excellent performance from the phono section; the C 328's onboard DAC was only slightly less distinguished, although it proved capable of more than 19 bits' worth of resolution, which is very good indeed. (Vol.41 No.10 WWW)

Peachtree Audio nova300: $1999★
With their nova300 integrated amplifier-DAC, Peachtree Audio made a number of transitions: from iPod docks to Lightning connectors and Wi-Fi; from tubed preamp buffers to all solid state; from line-only preamps to an onboard MM phono preamp; and, most notably, from Chinese to Canadian manufacture. Other characteristics endure, including the attractive wood wrap—made even more attractive by an Ebony Mocha finish option—and a class-D output stage, this one based on ICEpower modules, for a power rating of 300Wpc into 8 ohms. The nova300 also boasts double-DSD capability alongside 32/384 PCM, and Peachtree's Dynamic Noise Elimination (DyNEC), which is claimed to eliminate, among other noises, those associated with the display screens of smartphones and tablets. In a review that proved controversial, AD praised Peachtree Audio for the nova300's excellent phono section and for its overall good momentum and drive, but criticized the graininess of its treble range. In their Manufacturer's Comment in the same issue, Peachtree took issue with Art's pairing of the nova300 with his extremely efficient Altec Flamenco speakers, calling it a "mismatch," though they held out the possibility of a flaw in the review sample, which they said was "on its way to our engineers for a testing, just in case." We were disappointed never to have heard back about the first sample, which, in his measurements, JA described as having "a high level of switching noise on its output." However, for the December 2017 Stereophile AD wrote a Follow-Up based on a second sample of the nova300, which he tried with the very contemporary Wharfedale Diamond 225 speakers. Art thought this pairing sounded "slightly less edgy" than his earlier experience, although the sound remained "dry and crisp overall." (Vol.40 Nos.6 & 12 WWW)

PS Audio Sprout100: $799 $$$
Designed in Boulder, CO, and built in China, the PS Audio Sprout is a compact (6" W × 1.75" H × 8" D) integrated amplifier with built-in MM phono preamp, USB D/A processor, ¼" headphone jack—use of which automatically mutes the loudspeaker output—and Bluetooth receiver. In its original version, reviewed in the May 2015 Stereophile, the Sprout's class-D power amp could deliver up to 33Wpc across an 8-ohm load. In 2018 the Sprout underwent a redesign and was christened the Sprout100. Refinements include an increase in power, to 50Wpc into 8 ohms/100Wpc into 4 ohms—the latter spec surely the source of its name—and an ESS Sabre DAC chip that bumps up resolution from 24/192 to 24/384. Whereas HR thought the original Sprout sounded best through its phono input, he found the Sprout100 "exactly the opposite. Its digital input seemed more articulate and vivacious." In all, Herb appreciated the Sprout100 as "an easy-to-use lifestyle product," albeit one lacking in appeal to seasoned audiophiles. (Vol.38 No.5, Vol.41 No.11 WWW)

Rogers High Fidelity 65V-1: $4200 ★
The truly distinctive 65V-1 is a tubed stereo integrated amp whose output architecture is switchable between triode and Ultralinear modes. Also user-selectable are the 65V-1's output tubes: at the time of purchase, the buyer selects either EL34 or KT88 pentodes, although the tubes not taken, when purchased separately, can be used at any time, without the need for modification. Either way, the single-ended 65V-1 is said to produce less than 0.5% THD at 1Wpc and less than 3% at 10Wpc, with a peak output of 25Wpc. According to HR, with some music, the 65V-1 "let the vivid, undoctored reality of [the recordings] come through with eerie, preternatural directness." JA's measurements uncovered lower than specified output power—270mWpc at 1% THD, 2.275Wpc at 3% THD—as well as distressingly high output impedance. Independent of this, Herb concluded: "an uncommon audio product in search of uncommon audiophiles." In a Follow-Up, AD praised the ingenuity and audacity of bringing such an unabashedly fun product to the market, and noted the Rogers's abiding musicality. But through his DeVore O/93 speakers, he also heard a few "gritty" dynamic peaks from the 65V-1, which kept him from cozying up to the amp's sound. (Vol.41 No.6, Vol.42 No.1 WWW)

Editor's Note: There are no Class D integrated amplifiers listed.