Recommended Components

Editor's Note: Apart from the Bespoke, CAT, Placette, and Shindo, all the Class A preamplifiers offer balanced inputs and outputs. And unless noted, the preamplifiers listed do not have phono stages.

A

Audio Research REF6: $15,000
Replacing Audio Research's Reference 5 SE of 2011, the Reference 6 is a product in which everything—parts, circuitry, the whole megillah—has been revised, the upgrades including a heftier mains transformer, an improved volume-control circuit, and new custom-made capacitors. The audio circuits include three 6H30 dual-triode tubes per channel, while the power supply has one 6H30 and one 6550WE tube. The eight pairs of line-level inputs are evenly divided between single-ended (RCA) and balanced (XLR), alongside three pairs each of single-ended and balanced outputs. Among the Reference 6's electronically controlled functions are its 103-step volume control, signal-polarity inversion, and a mono switch. MF noted the Reference 6's unimpeachable specs, and reported that while listening to favorite recordings through it, he heard "intense surprises that I'm sure can't be measured. Record after record, I found that the Reference 6 greatly increased my understanding of very familiar recordings." In measuring the Reference 6, JA noted "superb channel matching," "inconsequential AC-supply noise," and, overall, "little hint of the presence of tubes in the circuit" (that last observation intended as a compliment). (Vol.39 No.12, Vol.41 No.10 WWW)

AVM Ovation PA 8.2: $10,595 base price; $19,995 as reviewed
A modular preamplifier that can be configured in a variety of ways, the Ovation PA 8.2 prevents the listener from having to invest in unwanted features, while taking into account the ever-changing world of digital audio: As technology progresses, AVM's current digital-input card ($3395), which supports up to 32/384 PCM and DSD256 and has both USB and S/PDIF inputs, can conceivably be replaced with even mightier modules. Other available input cards include an MM/MC phono preamp ($2395), a line input card with both balanced and unbalanced inputs ($1795), and a Line Input Tone Card ($2195) that provides tone and balance controls for all analog modules. The user also has a choice of output cards, including an optional Tube Output card ($3395) fitted with two dual-triode vacuum tubes. (A headphone amp and remote handset are included in the base price.) With line-level sources, Mikey noted "ultra-low" noise, "very high" transparency, "very good" dynamic expression, and "impressive" frequency extension and balance. In his view, the phono input offered "a level of sonic sophistication well above that of any $2400 phono preamp I've heard." In measuring the AVM preamp, JA noted "usefully low" output impedance, a distortion signature that was primarily second harmonic, and "superbly low" RIAA error from the phono card. "Overall," he wrote, "AVM's Ovation PA 8.2 offers superb measured performance." (Vol.41 No.12 WWW)

Ayre Acoustics KX-5 Twenty: $9950
The KX-5 Twenty line-level preamplifier enshrines almost all of the proprietary technologies that, in recent years, have put Ayre Acoustics on the map: Its Variable-Gain Transconductance (VGT) circuit adjusts volume not by throwing away varying amounts of gain but by adjusting, at its source, how much gain is created. Its active output buffer is based on Ayre's "diamond circuit" arrangement of bipolar transistors. And its AyreLock approach to voltage regulation creates, in essence, a push-pull power supply capable of turning on a dime in response to the demand dictated by the music signal. All of this is packaged in a non-huge aluminum enclosure described by AD as "tidy and evidently well laid out." Art was considerably less chipper about the KX-5 Twenty's user interface and owner's manual, for which he reserved such words as "unclear," "unneeded," "less than intuitive," and "both need work." He perked up again on hearing the Ayre's "remarkable and utterly nonclinical clarity, and its convincing, commandingly good spatial performance." Measurer-in-chief JA noted in particular the Ayre's "complete absence of power-supplyrelated" noise and its remarkably low distortion without reverting to loop negative feedback, declaring the KX-5 Twenty "superbly well engineered." In a Follow-Up, comparing the KX-5 Twenty with the similarly solid-state PS Audio BHK Signature, JCA noted the Ayre's drier sound and ability to "[carve] out a slightly deeper space," while giving the PS Audio pre the nod for controls and logistics. (Vol.41 Nos. 3 & 6 WWW)

Ayre Acoustics KX-R Twenty: $29,950 ★
It would seem an impossible task: improving on a preamplifier—the Ayre KX-R—that sounded better to JA than no preamplifier at all. But that was the hurdle set for the new KX-R Twenty, named in honor of Ayre's 20th year of operation. More of a complete redesign than an upgrade of the original, the KX-R Twenty employs AyreLock, a new, proprietary approach to power-supply regulation that seems equal parts calculus and poetry. Also involved were similarly big changes to the active circuitry, including the adoption, in this model, of the "diamond" output circuit of the company's X-5 series—if only because, in the words of then chief engineer, the late Charles Hansen, it proved to work "so insanely well." Of his time with the new Ayre, JA wrote, "Some highly resolving audio components achieve their transparency to what has been captured on a recording by emphasizing detail. The Ayre simply cleaned the window." JA's listening notes were ripe with examples of fine performance at various sonic tasks, but in the end, his view was holistic: "The Ayre evoked the words Peter Schaffer has Antonio Salieri saying, in Amadeus, about the entry of the solo oboe in this music: 'This was a music I'd never heard. Filled with such longing, such unfulfillable longing. It seemed to me that I was hearing the voice of God.'" (Vol.37 No.12 WWW)

Bespoke Audio Company Passive: $12,000 and up; $23,235 as reviewed ★
Built around a stereo pair of hand-wound, multi-tapped transformers, the Bespoke Audio preamplifier—which provides attenuation and source selection, but no gain—is a passive line stage that exudes an "unsurpassed" level of quality, according to AD. While declaring that he is not normally a fan of passive preamps, owing in particular to a paucity of musical impact in systems so equipped, AD noted that the Bespoke unit was better in that regard than he expected, and that its use brought enhanced clarity to some recordings; Bespoke Audio has, he believes, offered "the best justification yet" for the passive approach. In the June 2019 Stereophile MF wrote of borrowing a version of the Bespoke passive pre with all-silver-wire transformers and Furutech Rhodium input and output XLRs ($23,235), praising its "black" backgrounds and declaring it "the most beautiful" high-end product of his experience. (Vol.38 No.10, Vol.42 No.6)

Boulder 2110: $59,000 ★
Given that its predecessor, the model 2010, enjoyed a 17-year run in Boulder Amplifiers' product line, much was expected of the new 2110 line preamplifier: a multibox solid-state model in which user functions are optically controlled to eliminate noise, and whose six inputs are characterized by an impressive degree of adjustability and flexibility of configuration. All of its inputs and outputs are fully balanced, addressed only with XLR jacks, and the 2110 goes the 2010 one better by adding a fully differentially balanced volume control. Using the Boulder 2110 with his darTZeel NHB-18NS mono amps in balanced mode, MF observed that "[it] produced image intensity, physicality, and solidity that were unprecedented in my experience. First take: a giant Wow." MF elaborated: "It made recordings I know to be truly exceptional sound even more so through my system." With the Boulder pre on his test bench, JA observed, "The 2110's distortion is so low, in fact, that it taxed my ability to measure it." JA ultimately pronounced the 2110 "the best-measuring preamplifier I have encountered." (Vol.38 No.3 WWW)

Bryston BP17³: $4495 $$$
With its five single-ended inputs, two balanced inputs, and mix of single-ended and balanced outputs, the solid-state BP-17³ is the middle model of Bryston's three line-level preamplifiers. It can be customized with a variety of add-ons, including a MM phono stage ($750), a DAC ($750), and a remote-control handset ($375). Used with a Mark Levinson No.534 power amp (see "Power Amplifiers"), a fully equipped BP-17³ delighted LG with its ability to preserve bass weight and solidity when called for, and its no less impressive re-creation of recording-hall ambience. LG wrote that the Bryston "produced engaging, detailed, tonally captivating, utterly natural sound that approached reference quality," while noting, that matching with the correct amplifier is critical. JA's report from his lab on the "superbly well engineered" Bryston was similarly to the point: "It is difficult to see how a preamplifier could perform any better on the test bench!" (Vol.41 No.6 WWW)

Convergent Audio Technology SL1 Renaissance Black Path Edition: $19,995 line only, $21,995 with phono stage
The Convergent Audio Technology SL1, which has grown a long name to match its long life, continues to be revised and refined by designer Ken Stevens. In its Renaissance update, the heralded CAT SL1 line stage received a new circuit-board layout and improved power supply; it was also treated to an A/V bypass, user-selectable gain, and a switch-selectable, moving-coil transformer for its optional phono stage ($2000). Compared to its predecessor, the SL1 Ultimate, the Renaissance offered greater transparency, resolution, and dynamics, said RD. JA noted "superb measured performance and an equally superbly linear circuit topology." The most recent (2015) change was occasioned by CAT's development of their Black Path signal capacitor, and named for it; further audio-circuit optimizations and a reduction in noise intermodulation are also among the refinements claimed for the Black Path Edition. After spending time with the SL1 Renaissance, RD pointed to improved rendering of intertransient silence, crisper and tighter percussion sounds, and better transparency and resolution than from the SL1 Ultimate: "I knew I was hearing no minor improvement." (Vol.32 No.11, Vol.38 No.12 WWW)

darTZeel NHB-18NS Mk.2: approx. $44,000
The "stunningly transparent" darTZeel NHB-18NS of 2007 offered spectacular transient speed, resolution, and decay, while providing an overall coherence that "made recorded music, analog or digital, sound much closer to live," according to MF, who added that, with its warm, vivid combination of red case and dark-gold front and rear panels, the NHB-18NS "looks like it sounds." As of the summer of 2008—by which time he'd bought one for himself—MF felt that the battery-powered NHB-18NS matched the resolution and transparency of MBL's 6010 D preamp, while managing to sound less mechanical. Despite the similar name, the NHB-18NS Mk.2 of 2017 is a complete redesign of the Swiss company's preamp but still offers both line and phono stages—the latter, per MF, being "sonically far superior to the original," and more adjustable than many outboard phono preamps of his experience. MF also hailed the new model's digitally displayed volume-control calibration, and the fact that, unlike that of its predecessor, the new model's batteries "have never run out of juice during a listening session." According to Mikey, the new darTZeel's phono section sounds "neither as transparent nor as dynamic" as the far more expensive outboard Swiss Precision P1 ($31,000 without additional power supply) or Ypsilon VPS-100 Silver Edition ($65,000). That said, with the "tube-like richness and generous flow" it inherited from its forebear, the Mk.2 "will more than satisfy casual vinyl listeners." (Vol.30 No.6, Vol.31 No.10, Vol.33 Nos. 5 & 10, Vol.40 No.6 WWW)

Lamm Industries L2.1 Reference: $26,590
The greatest accomplishments of Vladimir Lamm's electronics are like those of the art restorer who removes grime and soot without diminishing the vibrant colors beneath—so believes AD, who said of Lamm's latest line stage, the two-box L2.1 Reference, "[it] reproduced the sounds of bowed and plucked strings alike with color, texture, and humanness." The Lamm does so with an unorthodox combination of technologies: high-voltage MOSFETs in the all–single-ended gain stages; and tubes throughout its power supply, for rectification, regulation, and the amplification of voltage references. The L2.1 Reference, which differs from its predecessor in its use of new current-source transistors and other recently available components, offers switchable signal-phase inversion and easily adjusted channel balance—the latter thanks to its dual-mono volume potentiometers—and further delighted AD by eschewing remote control. His verdict: "the rare product that swept the question of tubes vs solid-state into insignificance." Writing from his test bench, JA noted the Lamm's "extraordinarily low" distortion and observed that, "like the other preamplifiers designed by Vladimir Lamm that have passed through my test lab, the L2.1 Reference is well engineered." In his Follow-Up, JVS noted that the L.2.1's presence in his system extracted the best from the Bricasti M15 stereo amp (see "Power Amplifiers"), writing that "the L2.1 did a bang-up job with percussion, restored the horns' natural bite and heat, and enhanced the three-dimensionality and musical intensity." In a different context and with a different recording, he acknowledged that the Lamm "toned down and softened a smidge" the natural edge on a singer's voice while adding, "That is not necessarily a bad thing." (Vol.40 No.7, Vol.41 No.7 WWW)

Mark Levinson No.526: $20,000
Pricewise, the No.526 occupies the slot between Mark Levinson's No.326S ($10,000) and No.52 ($30,000), and offers both line-level and MM/MC phono preamplification in a single box. The fully balanced No.526 also has an ESS Sabre-based 32-bit DAC with user-selectable PCM and DSD filter options—AES/EBU, S/PDIF, and USB inputs are provided—and a "digital-restoration" module that parent company Harman International calls Clari-Fi. In the manner of other contemporary microprocessor-enhanced preamps and integrated amps, individual inputs can be customized with the user's choice of names, gain offsets, etc., and provisions are offered for network connection (Ethernet) and firmware updates (USB). The No.526's "sheer clarity, startling transparency, [and] liquid midrange" impressed LG, who observed that the preamp's "qualities of design and manufacture let me be drawn into the music as never before." Writing from his test bench, JA said that, "Overall, the Mark Levinson No.526 offers superb measured performance." (Vol.40 No.5 WWW)

Pass Laboratories XP-22: $9500
The two-box, solid-state, line-level Pass XP-22 provides both balanced (XLR) and single-ended (RCA) inputs and outputs, plus a vestigial tape loop. The XP-22's volume control—an Avago-sourced encoder that JCA describes as having "good bearings and a nice feel"—is the same one used in Pass's upmarket XP-30, and balance is adjustable via a chunky metal handset that "duplicates all front-panel controls, and then some." JCA heard "impressive" bass impact, "pinpoint" imaging within a large soundstage (albeit one that shrank a little at lower volumes), and sound that "seemed a tad more open" than with his reference preamp. In measuring the XP-22, JA found "superb" channel separation, "extremely low noise," an "excellent" (85.35dB) audioband S/N ratio, and "extremely low" THD+N: "superb measured performance." (Vol.42 No.6 WWW)

Pass Labs XP-30: $16,500 ★
In its conventional two-channel mode, the XP-30 comprises three separate chassis: one each for its control circuitry and power supply and each channel's audio circuitry. Using additional chassis, the XP-30 can be expanded to as many as six channels. Each audio chassis has both a Master and a Slave analog output, duplicated on balanced XLRs and single-ended RCAs; and six analog inputs, also duplicated on balanced XLRs and single-ended RCAs. The XP-30 uses an integrated-circuit volume control. It virtually transported JA to recording studios and performance spaces, consistently drawing his attention to aspects of music rather than of sound. "The XP-30 has rekindled for me the concept that the beating heart of an audio system is the preamplifier," he said. Measured performance was superb. (Vol.36 No.4, Vol.38 No.5 WWW)

Placette Audio Active LineStage: $6995
The Active Linestage is intended to combine the transparency of Placette's purist Remote Volume Control with a usable level of functionality, providing five sets of unbalanced inputs, two sets of outputs, and a tape loop. Its absolute clarity, focus, solidity, and transparency were unrivaled in BD's experience. "Highly recommended." Sold direct, with a lifetime warranty and 30-day refund policy. (Vol.30 No.11 WWW)

PrimaLuna EVO 400: $4499
PrimaLuna's brand-new flagship line-level preamp—it replaces the company's DiaLogue Premium—the EVO 400 uses tubes for rectification as well as for gain and buffering, and includes input and output transformers that allow balanced operation. Noting that its extraordinary weight (52.8lb) comes not from its steel chassis but from its abundance of power-supply transformers and chokes, HR praised the EVO 400's very high parts quality and lavished similar praise on its "scintillating" presentation and ability to portray vivid, well-saturated musical colors while nevertheless being "more concise-sounding" than its predecessor in the PrimaLuna line. "It generated clearer, more muscular presentations with sharper focus and more distinctly punctuated momentums." Reporting from his test bench, JA noted that "the EVO 400 measures well for a tubed design." (Vol.42 No.7 WWW)

PS Audio BHK Signature Preamplifier: $5999 ★
Like its stablemate BHK Signature 300 monoblock amplifier, the BHK Signature preamplifier is named for its designer, Bascom H. King. Also like that monoblock, the BHK Signature preamp is a hybrid product, using both transistors (N-channel MOSFETs, also as in the BHK amp) and tubes (two 12AU7 dual-triodes, also put to work in the preamp's distinctive volume-control system, whereby some sound-level increments are achieved not through changes in resistance but through changes in tube-stage gain). Ten line-level inputs are divided evenly between single-ended (RCA) and balanced (XLR) jacks—there is no phono stage—as are the two outputs. Apart from noting that the above-mentioned volume-control system emitted an occasionally, barely perceptible noise that was ultimately masked by the music, JCA was impressed: after comparing the BHK Signature with nothing at all—that is, with the sound of a system in which a DAC drove a pair of PS Audio BHK Signature 300 monoblocks directly—JCA wrote: "With the BHK Signature preamplifier in the system, the music seemed more lively, and the space in which the images were cast was more tangible." Writing from his test bench, JA observed: "this preamplifier measured superbly." In his June 2018 Follow-Up, JCA compared the BHK Signature—now his reference—to the Ayre Acoustics KX-5 Twenty, noting that, by comparison, the PS Audio "softened . . . transients just a touch, slightly polishing the edges." But he found much to enjoy in both, and declared his BHK Signature "honest and musical." (Vol.40 No.6, Vol.41 No.6 WWW)

Rogue Audio RH-5: $2495 $$$
The Rogue RH-5 is a headphone amplifier and line-level preamplifier that offers three user-selectable levels of gain, and whose hybrid circuitry includes MOSFET transistors and two 12AU7 dual-triode tubes. It provides four line inputs—one balanced (XLR) and three single-ended (RCA)—as well as one set each of balanced and single-ended outputs, all on its rear panel. On its front panel are three headphone outputs: one three-pin XLR and two studio-grade sockets, each combining a three-pin XLR and a ½" phone jack. The Rogue allows two pairs of headphones to be used simultaneously. As a preamp, the RH-5 impressed HR with its "full-bodied sound," and did such a good job with Morphine's At Your Service that Herb was compelled to write, "I nearly drowned in this mesmerizing river—and for that I blame the Rogue RH-5's ability to submerge me in its every undercurrent and textured nuance." As a headphone amplifier, the Rogue "possessed the resolution, forcefulness, and transparency of a superior line stage," and excelled at driving low-sensitivity 'phones. HR noted that the RH-5's optional MC phono stage ($400) was "a super value" but lacked nuance in comparison with more expensive outboard phono preamps. Writing from his test bench, JA noted that the Rogue will perform its best with power amps whose input impedances are greater than 20k ohms, and concluded by describing the RH-5 as "a well-balanced design." (Vol.40 No.11 WWW)

Rogue Audio RP-7: $4995
This line-level preamplifier uses four 12AU7 dual-triode tubes and contains 17 (!) separate power supplies, including an individual regulated filament supply for each tube. Its military-spec circuit board is endowed with heavy copper traces and graced with an abundance of Vishay HEXFRED diodes, Vishay resistors, and Mundorf oil-caps. The Rogue's rear panel is itself abundant with connectors: three unbalanced (RCA) line-level inputs, two balanced (XLR) line-level inputs, and two each unbalanced and balanced outputs, following the same connector conventions. The front panel is notable for more than just its single ¼" headphone jack and its old-school volume knob: It also includes a Balance knob, which HR loved. Used in conjunction with HR's First Watt SIT-3 solid-state amplifier, the Rogue preamp delivered "a superbly balanced and invigorating—nay, intoxicating—system that didn't sound like tubes or solid-state. But it did reproduce, with extraordinary weight and saturated tones, my latest favorite piano album." Herb's conclusion: "My new reference." In measuring the RP-7, JA found that, "as long as it's driving a power amplifier with a high input impedance, Rogue's RP-7 offers generally respectable measured performance." (Vol.42 No.3 WWW)

Shindo Monbrison: $12,500
Some months after the death, in 2014, of founder Ken Shindo, Shindo Laboratory's long-lived, second-least-expensive preamp, the Monbrison, vanished from the line—a consequence, many presumed, of the company's having run out of Monbrison-specific enclosures and other parts. Soon after, their next-most-expensive preamp, the Masseto, also disappeared. Both products have now been replaced by an all-new preamplifier: a Monbrison in name but a Masseto in function. (Unlike the Monbrison and like the Masseto, the new model is designed and built with output transformers.) The new Monbrison is also the first of Shindo's full-function preamps (ie, it includes both line and phono stages) to be designed by Ken Shindo's son, Takashi Shindo, who departed from previous Monbrisons by eliminating one of two sets of phono inputs (and onboard step-up transformers) but retained their use of ECL 94S triode-pentode tubes for line-level gain and 6X4 diodes for rectification. Shindo's signature steel casework endures, but now the Monbrison's enclosure is a two-level structure, as in the company's most expensive preamps. After a lengthy break-in period in AD's system, the Monbrison "demonstrated nuances of expression I've never heard from the Masseto: The new Monbrison doesn't just convey momentum—rare though that talent is in the larger context of consumer audio—but begins to hint at the emotional and intellectual energies of the players." AD added that the Monbrison is "realistically, generously colorful, and expresses sonic textures convincingly and without etch," and praised it for providing "greater listening pleasure than any other preamplifier I've had in my system, save for the considerably more expensive Shindo Vosne-Romanee." (Vol.40 No.9 WWW)

Sugden Masterclass LA-4: $3750
Sugden's solid-state, line-level-only Masterclass LA-4 offers four single-ended (RCA) inputs and one balanced (XLR) input, with outputs of both of those types. (The circuitry is fully balanced overall.) Gain is generous—JA would measure ca 20dB, single-ended or balanced—with signal attenuation courtesy of an old-school volume control. With the Sugden in his system, JCA noted "more ambiance with good recordings" than through his reference PS Audio preamp, but also "a touch less body." Overall, the Masterclass LA-4 "subtly illuminated the music," and "preserved subtle soundstage cues." JA's measurements uncovered lower-than-specified output impedance, thus indicating good compatibility with a variety of power amps, but a "disappointing" wideband S/N ratio. (Vol.42 No.4 WWW)

VAC Signature SE: $19,500 (line stage only), $26,000 (with phono) ★
In its basic form, the Signature SE ($19,500) is a tubed line stage that offers a mix of balanced (XLR) and unbalanced (RCA) inputs and outputs, the latter addressed by custom-designed output transformers. Its optional phono stage ($6500)—dual-triode tubes, MC step-up transformers, separate power-supply transformer, and all—fits alongside the line-level circuitry in the preamp's main enclosure. (A second, separate chassis is devoted to the line stage's power supply.) In his last review for Stereophile, our beloved friend BJR described the VAC Signature SE as nothing less than "the most significant audio product I've ever hooked up to my reference system. It was flawless." Noting, in his measurements, some frequency-dependent "poor overload margin" and "high intermodulation distortion" in the VAC's phono stage, JA recommended partnering the preamp only with phono cartridges of lower-than-average output. (Vol.38 No.6 WWW)

VTL TL6.5 Series II Signature: $18,000
Essentially a single-box version of VTL's TL7.5, the fully balanced TL6.5 Series II Signature line-level preamplifier combines a gain stage based on vacuum tubes—one 12AU7 per channel—with an output stage using solid-state devices. For the Series II version, those devices have been upgraded from MOSFETs to an unidentified type of FET that VTL says is more tube-like in its behavior. Other technical changes include the elimination of global feedback and a doubling-up of mains transformers. FK described the TL6.5 Series II Signature as "the smoothest-sounding preamp I've heard in my system—and I don't mean smooth in a pejorative sense." He also described extended trebles that were "pure" and "natural," abundant speed and consequent added realism on percussive sounds, and good imaging "without excessive beam." JA's measurements confirmed the VTL's high quality: "The TL6.5 Series II Signature is a well-engineered preamplifier—as I have come to expect from VTL." (Vol.39 No.8 WWW)

Ypsilon PST-100 Mk.2: $37,000 ★
Made in Greece, the PST-100 is a handsome tubed preamplifier housed in a thick, satin-finished aluminum chassis. It features transformer-based attenuation, 6CA4 tube rectification, choke supply filtering, a switchable passive mode, and a zero-feedback active stage based on a carefully selected Siemens C3m pentode tube. Though differences between the PST-100's active and passive stages were small, MF preferred the passive stage for its purer, more transparent sound. Compared to the darTZeel NHB-18NS, the Ypsilon produced more vivid tonal colors and greater physicality. "For now," MF concluded, "the Ypsilon PST-100 is the most transparent and, therefore, the most perfect audio component I have ever heard—or not heard." Though XLR input and output jacks are provided, the circuitry is unbalanced only. Without a line stage, the completely passive PST-100 TA costs $26,000. (Vol.34 No.7 WWW)

B

AudiaFlight FLS1: $6995
The made-in-Italy FLS1 is a solid-state line-level preamplifier with a fully balanced architecture—both single-ended (RCA) and balanced (XLR) inputs and outputs are provided—and a built-in headphone amplifier. Extra-cost options include a phono-preamp board with MM and MC inputs and adjustable loading ($1000) and a DSD-friendly DAC board ($2000), the latter of which was unavailable at the time of our review; both are user-installable. All of the FLS1's user interfaces are microprocessor controlled, with the aid of an OLED screen and a system of nested menus; all were described as "elegant" and "easy" by reviewer MF, who also noted that "the feature-packed FLS1 doesn't look, feel, or sound as if Audia Flight has compromised on quality," and described the sound on both line and phono inputs as leaning "somewhat toward the warm, midrange-rich side." In measuring the Audia Flight pre, JA found "superbly low" RIAA error, and concluded that, "overall, Audia Flight's FLS1 offered simply superb measured performance." Phono card adds $1000; DAC card $2000. (Vol.42 No.4 WWW)

PrimaLuna ProLogue Premium: $2199
PrimaLuna, a company that has been linked to a recent worldwide shortage of uppercase letters, designed this old-school, line-level tubed preamp in the Netherlands and builds it in China to "levels of quiet, durability, and sonic sophistication not possible in the 20th century," according to HR. The tube complement comprises four 12AU7 dual-triodes and a dual-mono pair of 5AR4 rectifiers, the latter an unusual choice in an era when so many preamp manufacturers economize by using solid-state rectifiers. Five single-ended inputs are offered, alongside two single-ended outputs and a tape out; a remote handset is supplied to control the ProLogue Premium's motorized Alps volume control, if desired. Used in a system that included, at times, PrimaLuna's ProLogue Premium power amplifier (built into an identical blue-gray steel enclosure), the ProLogue Premium preamp impressed HR with its "feminine and seductive" sound. While cautioning readers that the PrimaLuna's high (2800 ohms) output impedance demands a partnering amplifier with an input impedance not lower than 28k ohms, Herb observed that the owner of a properly set up ProLogue Premium preamp will enjoy "tangibly luminous presence in every recording you play. Punch and drive should be obvious. . . . Most of all, you should notice [its] liquid transparency." JA reported that the ProLogue Premium preamp "generally measures well," but he did discover a second-harmonic distortion signature that could be counted on to "fatten up the sound." (Vol.40 No.6 WWW)

Rogue Audio RP-1: $1795
The latest example of an encouraging trend toward preamplifiers with built-in phono stages, the Rogue RP-1 uses a pair of 12AU7 dual-triode tubes for line-level gain and buffering, and solid-state devices for MM and MC phono preamplification, the latter including eight choices for user-adjustable cartridge loading, ranging from 30 ohms to 47k ohms. Creature comforts include a balance knob—as HR wrote, "when was the last time you saw one of those?"—as well as a front-mounted headphone jack and a remote handset. HR did not mince words: apart from describing the Rogue's headphone sound as "mostly average," he wrote that, "compared to any preamplifier I know of at anywhere near its price, the RP-1 reaches deeper into the music to excavate a stronger, more precise, more spacious musical presentation. Highly recommended." Apart from confirming that its headphone amp rolls off the highs (5dB at 20kHz) and that its output impedance requires a partnering amp with an input impedance no lower than 10k ohms, JA reported that the RP-1 measured well—and described its phono stage as "simply superb." (Vol.39 No.8 WWW)

Editor's Note: There are currently no Class C preamplifiers listed.

K

Benchmark Media LA4 Line Preamplifier.

Deletions
Parasound Halo JC2 and P7, Schiit SYS.