Recommended Components

Editor’s Note: Because of the disparity between typical tube and solid-state “sounds,” we have split Class A for separate power amplifiers into two subclasses. Nevertheless, even within each subclass, Class A amplifiers differ sufficiently in character that each will shine in an appropriate system. Careful auditioning with your own loudspeakers is therefore essential. Except where stated, output powers are not the specified powers but rather those we measured into an 8 ohm resistive load. All amplifiers are stereo models, except where designated.

A (Solid-State)

Aesthetix Atlas: $8000
Offering 200Wpc (318Wpc at clipping), the Atlas has a tubed input stage, a solid-state output stage, and a second pair of inputs with a 6dB/octave high-pass crossover that can be set to 16 different corner frequencies from 40 to 200Hz. Build quality is top-notch and rugged, with the amp’s body wrapped in an aluminum enclosure that surrounds the circuits and heatsinks in a cage-in-cage construction. The Atlas was characterized by a control, ease, and dynamic command that allowed music to jump to life, said WP. Compared to the Parasound Halo JC 1, the Atlas offered a creamier midrange, but lacked a little top-end extension and bottom-end body. (Vol.33 No.1 Read Review Online)

Ayre Acoustics MX-R monoblock: $18,500/pair ✩
Relatively small (11" W by 18.75" D by 3.75" H) for a 300W monoblock, the MX-R is carved out of a 75-lb billet of aluminum, and uses a zero-feedback, discrete design with a dual-transformer power supply whose custom-made trannies are built to fit the MX-R’s unique shape—a shape that provoked WP’s audio lust: “a hunka hunka shiny, anodized audio presence,” as he described it. “It’s too physical to look cute and too sleek to look like a monster amp.” Though the MX-R exhibited “a clangy opacity when cold” and required break-in to reach maximum performance, its unrivaled presentation then captured the clarity of individual instruments as well as the musical whole. “Second to none,” said Wes. Comparing the MX-R with the Krell Evolution 600s, the sonic differences between the amplifiers were “extremely subtle,” said WP. However, while the Krells drew Wes’s attention, especially with superbly recorded material, the Ayres inspired him to deeply mine his entire music collection. (Vol.30 No.4 Read Review Online)

Ayre Acoustics V-5xe: $4950 ✩ $$$
The compact, beautifully built V-5xe delivers 150Wpc into 8 ohms and features single-ended and balanced inputs and speaker-wire terminals made by Cardas. Though it lacked some power in the bass and sacrificed “a little of that you-are-there-ness” produced by the best single-ended-triode amps, the V-5xe offered a highly resolving, dynamic, harmonically pleasing sound that was never fatiguing. “Open, airy, and sweet,” said ST. “What more do you want?” (Vol.29 No.5)

Bel Canto Ref1000M monoblock: $5990/pair ✩
Outwardly identical to the original Ref1000, the 500Wpc 1000M uses an updated version of B&O’s ICEpower module, a more complex input board, and a new power-supply board. The new Bel Canto was “dead silent” and sounded “clean, powerful, and neutral,” with a heftier bottom end and a more natural midrange. No longer marked by the shortcomings of other digital amps, the Bel Canto “can be compared with the cream of the other amps I’ve had in my system,” enthused Kal. JA’s measurements revealed the REF1000 Mk.2 to be very powerful, delivering 600W into 8 ohms or 1200W into 4 ohms. It will work best with higher-impedance loudspeakers, however, and at lower frequencies. (Vol.32 No.3, Vol.33 No.7 Read Review Online)

Classé CT-M600 monoblock: $13,000/pair
Classé CA-M600 monoblock: $14,000/pair
In a mundane-looking black box with a detachable rack-mount front panel that matches the styling of Classé’s CT-SSP preamplifier-processor, the CT-M600 is rated to deliver 600W (700W at actual clipping) into 8 ohms. It employs Classé’s Intelligent Cooling Tunnel, in which internal heatsinks are mated to a microcontroller to actively ensure a thermally stable environment. All the audio circuitry, including the 36 output devices, is carried on two six-layer boards, allowing signal paths to be very short and keeping the amplifier’s noise floor very low. The CT-M600 was the “consummate chameleon,” drawing the best from a wide variety of loudspeakers, providing enormous dynamic range, deathly quiet backgrounds, and intensely saturated colors. “They are the best-sounding amplifiers I have auditioned in my system,” said JA. Compared to the massive Musical Fidelity AMS100, the CT-M600 offered better upper-bass definition and slightly more upper-frequency energy, but lacked the AMS100’s sweet, forgiving treble, said JA. The CA-M600 is essentially the same amplifier, housed in Classé’s traditional Delta-series enclosure, with its brushed-aluminum front panel curved around to form the side panels. (Vol.34 Nos.3 & 9 Read Review Online)

Electrocompaniet AW400 monoblock: $12,500/pair
Claimed to deliver 400W, the AW400 is a push-pull design optimized for true balanced operation. Its tall front panel is a nicely finished sheet of clear acrylic, backlit in blue, complementing the amp’s fine overall construction. While it didn’t match the graceful, surefooted musical flow of AD’s favorite low-powered amps, the AW400 offered a solid yet open sound marked by excellent clarity, impact, and scale. “The Electrocompaniet AW400 is a sweet, fun, and unabashedly powerful-sounding amp,” concluded Art. JA was impressed by its low levels of noise and distortion. (Vol.33 No.9 Read Review Online)

Lamm Industries M1.2 Reference monoblock: $23,890/pair ✩
The 110W M1.2 with tube front end and MOSFET output stage, comprehensive short-circuit protection, and high/low impedance settings, offered “unflinching honesty in conveying the true nature of the music that passed through it,” said PB. “Utterly continuous and coherent from top to bottom,” the M1.2 combined resolution and transparency with harmonic completeness, timbral richness, and glow. JA concurs. (Vol.28 No.2, Vol.35 No.4 Read Review Online)

Luxman B-1000f monoblock: $55,000/pair
The heart of the 250W (310W at actual clipping) B-1000f is its transformer, wound with flat, 2mm-thick copper bar, insulated with paper, and meticulously hand-hammered around the core. Each section of the amp is isolated from all others by shielding and internal filtering, and Luxman’s proprietary Only Distortion Negative Feedback topology is used to further isolate noise and distortion from the music signal at the input. The B-1000f exhibited a “palpably lifelike sound” marked by impressive solidity and jump factor, stable stereo imaging, and natural dynamic ease. “Possibly the finest amplifier I have ever auditioned,” said WP. (Vol.34 No.2 Read Review Online)

Luxman M800-A: $19,000 ✩
The 160Wpc M-800A weighs 107 lbs, has an output stage that runs in class-A for the frst 60W, and offers an outstanding level of build quality and fit’n’finish. The M-800A had no difficulty driving MF’s Wilson MAXX 2 loudspeakers. It offered a warm, lush sound without sacrificing immediacy, transparency, or transient clarity, but couldn’t match the low-level dynamic contrasts of the Musical Fidelity kW monoblocks. “I can love and respect the Luxman M-800,” MF concluded. (Vol.31 No.11 Read Review Online)

Mark Levinson No.532H: $8000
Inside its modest-looking, no-nonsense black chassis, the 300Wpc (355Wpc at clipping) No.532H houses two 436VA toroidal transformers, independent power-supply components for each 16-output-device channel, curved PCB traces, and a fully differential circuit for the signal path. LG was impressed by the No.532H’s “superior bass slam, soundstaging, treble detailing, midrange pitch definition, and jaw-dropping dynamic range.” JA noted “textbook measured performance,” with high power output and very low levels of noise and distortion. (Vol.34 No.8 Read Review Online)

mbl 9011 Reference monoblock: $106,000/pair
The 440W (540W at actual clipping into 8 ohms) 9011 measures 19" W by 13" H by 34" D, weighs 223 lbs, is available in several high-gloss finishes with accents in chrome or gold plate, and can be used as a stereo amp or bridged monoblock. Though it lacked some speed and bass punch in absolute terms, the MBL produced a rich midrange and excelled in scale, atmosphere, ease of presentation, and sheer power, said MF. When used as a bridged monoblock, the 9011 must be driven by a balanced signal, cautioned JA, who noted superb measured performance. (Vol.35 No.3 Read Review Online)

mbl 9007 Noble Line monoblock: $42,800/pair ✩
The 440W Reference 9007 can be used as either a balanced monoblock or a single-ended stereo amplifier and has provisions for biwiring and biamping. It uses mbl’s Direct Push/Pull circuitry design and Isolated Gain Cell technology, and its gleaming black exterior is decorated by a large, gold mbl logo. Sacrificing bloom and suppleness for crystalline transparency and offering tightly focused imaging, shimmering highs, and well-damped bass, the 9007 was one of the most exciting and engaging amplifiers in MF’s experience. His recommendation only concerns the 9007 used as monoblock pairs, however. JA was thrilled by the mbl’s superb measured performance. Compared to the humongous Musical Fidelity AMS100, the MBL monoblocks were a little more forward in the low treble and offered more ultimate slam, but lacked the AMS100’s sweet, forgiving treble, said JA. (Vol.29 No.9; Vol.34 No.9 Read Review Online)

Musical Fidelity Titan: $30,000
The fully balanced, dual-mono, two-chassis Titan is rated to deliver 1kWpc into 8 ohms. Though only slightly more than 7" high, each box is 19" wide and more than 2' deep. The 150-lb power supply houses two 3kVA toroidal mains transformers and a pair of toroidal chokes, while the 100-lb amplifier section contains 40 output devices. Regardless of volume level or source material, “the Titan produced luxurious, velvety, enveloping warmth, along with precise imaging, a huge, stable soundstage, and a nimble rhythmic drive,” said MF. Compared to the Bryston 7B SST2, the Titan offered far superior image focus, richer instrumental textures, and a greater sense of space, said MF. JA, too, was impressed: “Technically, this is an extraordinary amplifier.” Production is limited to 40 units. (Vol.32 No.6, Vol.33 No.1 Read Review Online)

Musical Fidelity AMS100: $19,999
A massive beast: The 100Wpc, class-A AMS100 measures a staggering 19" W by 12.75" H by 34.67" D, weighs 220 lbs, and, even when not playing music, draws 10 amps from a typical 120V wall supply. Hot and cold speaker terminals for each channel are each driven by a complete mono amplifier. Additionally, each channel has a separate transformer and a bank of 16 supply capacitors, each bank fed rectified DC via a hefty, dual bifilar-wound choke designed to filter and cancel ripple on the two voltage rails. The AMS100 combined outstanding resolution with a seductively sweet midrange to create a relaxed, forgiving overall sound, said JA, and its excellent measured performance was marked by impressively low static distortion. “Musical Fidelity’s AMS100 is magnificent. It is also silly,” JA said plainly. (Vol.34 No.9 Read Review Online)

Parasound Halo JC 1 monoblock: $9000/pair ✩ $$$
MF heard exactly what this high-power—400Wpc specified, 586W at clipping!—John Curl-designed amp’s specs showed: “ultra-wide bandwidth, high-current capability, low, low noise, a high S/N ratio, and a fast slew rate, among many other indicators of outstanding amplifier performance....There was an honesty to the overall tonal and harmonic presentation that transcended technological stereotypes.” MF found the overall sound to be powerful, refined, smooth, organized, dynamic, transparent, and rhythmically supple, if a little on the subtly warm and rich side of the sonic spectrum, but decided that this not at the expense of transient speed and resolution of detail. “Perhaps some listeners will find the JC 1 too refined and perhaps a tad polite, but I didn’t.” “Rocks for sure,” says ST, adding that with the amp driving the Triangle Magellans, he found the “bass firmed up, the sound wasn’t strained in any way, and there was an overall sense of ease. Dynamic ease. Listening ease. Just ease. Compared to the Halcros, the Parasound JC 1s brought the soundstage forward. Tonally, the Parasounds were magnificent...with no trace of solid-state hardness. And the amps weren’t even broken in.” “The Parasound JC 1 is one of the finest high-powered solid-state amps I’ve heard,” said ST. “Think of it as a 25W class-A amp that does 400W class-A/B when pushed.” Matched with the JC 2 preamp, the JC 1s presented even greater holographic detail and transparency. The Parasound Halo JC 1 traded the Moscode 402Au’s snappy, vivid tonality and larger soundstage for “quiet precision,” clarity, and focus, said WP. The Halo JC 1 traded the Aesthetix Atlas’s creamy midrange for greater bottom-end heft and top-end extension, said WP. Compared to the Bryston 7B SST2, the Parasound had deeper bass, tighter images, faster transients, and greater low-level resolution and microdynamic delicacy, said MF. A favorite of JA’s, who was equally impressed by how the JC 1 performed on the test bench: “This is excellent measured performance. The Halo JC 1 is not only the best amplifier to come from Parasound, it ranks up there with the best high-end heavyweights,” though WP felt that while the Halo JC 1 exhibited grace and delicacy compared with the much more expensive Luxman B-1000f, it lacked some impact, drive, resolution, and detail. Stereophile’s—and Sam Tellig’s—“Joint Amplification Component” for 2003. (Vol.26 Nos.2, 6, & 12, Vol.30 No.12, Vol.31 No.3, Vol.32 No.9, Vol.33 No.1, Vol.34 No.2 Read Review Online)

Pass Labs XA30.5: $5500
This solid-state stereo power amplifier from renowned engineer Nelson Pass is rated to deliver 30Wpc into 8 ohms, but actually delivered clipping-free peaks 6dB higher in power. Its strong yet elegant physical appearance is matched by a simple, symmetric internal design using Pass’s Universal Gain Stage and 10 pairs of power MOSFETS along each side of the rugged chassis. Though it lacked the snap and energy of some larger, more powerful amplifiers, the XA30.5’s “lifelike smoothness” and “effortless purity” brought forth the subtle microdynamic nuances of more intimate material. BD: “The XA30.5 is a superb-sounding amplifier. Absolutely, positively, and enthusiastically recommended!” Compared to his reference Pass Labs Aleph 3, the XA30.5 had a leaner midrange but provided a wider soundstage, greater resolution, and better dynamics, EL concluded. Compared to the tubed Rogue M-180 monoblock, the XA30.5 offered a slightly more forward sound that was “rounder, richer, less controlled but more sumptuous” overall, said EL. The XA30.5 traded the Pass INT-150’s bass control and wide dynamics for greater purity and texture in the midrange, said EL. (Vol.32 Nos.5 & 8, Vol.33 No.1, Vol.34 No.1 Read Review Online)

Plinius SA-103: $10,150
The SA-103 delivers 125Wpc into 8 ohms and has an output stage that can be operated in class-A or class-A/B. Its large (19.75" W by 8.75" H by 18" D) chassis is dominated by generous heatsinks that unfurl from the amp’s side panels like fronds of fern. EL was most impressed by the SA-103’s accurate soundstaging and well-controlled, articulate bass performance. He summed up: “The Plinius SA-103 offers a natural, neutral tonal balance, just the right amount of musicality, superb bass performance, plenty of current to drive the most piggish speakers, [and] functional and tasteful design.” In class-A/B mode, the Plinius suffered from insufficient output-stage bias current; class-A operation is to be preferred, decided JA. (Vol.34 No.4 Read Review Online)

Simaudio Moon Evolution W-7: $9500
Styled to match the Moon Evolution P-7 preamp, with a black front panel flanked by brushed-aluminum cheeks and with black heatsink fins along each side, the W-7 is a fully balanced, dual-mono design with JFETS used for the input stage and 12 bipolar transistors biased to run in class-AB for each channel’s output. Rated to deliver 150Wpc into 8 ohms, the W-7 reached 200Wpc at actual clipping. JA noted silky highs, a smooth and clean midrange, a well-controlled bottom end, and huge dynamics. Measured performance was equally impressive. JA: “Powerful, with an iron hand on the loudspeakers, and superbly quiet, the W-7 excels without calling attention to itself.” (Vol.32 No.5 Read Review Online; see also RD’s Monitor Audio review in Vol.33 No.4.)

Soulution 710: $50,000
The 130Wpc Soulution is a dual-mono, dual-differential design housed in a large (21" W by 10.9" H by 18.7" D), clean, matte-gray case. Two massive 1000VA toroidal transformers, solid copper bars carrying rectifiers and capacitors, and a thick, heat-dissipating aluminum baseplate contribute to the amp’s 176 lbs. The Soulution offered unparalleled transparency, startling transient clarity, and impressive soundstaging, but lacked some harmonic richness and bass impact. “A technical and sonic achievement not to be denied,” said Mikey. With impressive dynamic range and exceedingly low levels of noise, the Soulution proved one of the best-measuring amplifiers in JA’s experience. (Vol.34 No.8 Read Review Online)

A (Tube)

Balanced Audio Technology VK-55SE: $5995
Balanced Audio Technology VK-55: $3995 ✩ $$$
Like its preamp partner, the VK-3iX, the tubed, 55Wpc VK-55 features improved fit’n’finish and ergonomics over its predecessors. In combination with the VK-3iX, the VK-55 gave RD’s system a vanishingly low noise level and produced music that was convincingly real. On its own, the VK-55 delivered firm, extended bass and presented high-level dynamics with ease. “The BAT VK-3iX and VK-55 are exemplars of the best that specialist home audio has to offer,” said RD. The “unerringly musical” VK-55SE delivers 55Wpc into 8 or 4 ohms. Upgrades from the standard VK-55 include new capacitors, an improved power supply, and the use of two 6H30P tubes in the amp’s gain stage. Fit’n’finish were superb, with substantial metalwork and flawless livery in textured black. Though it lacked the energy reserve of the 200Wpc Aesthetix Atlas, the BAT had a sound that was always “vivid, relaxed, and liquid,” said WP. The BAT’s grain-free, uncolored, and quiet sound worked to reproduce music in a way that came “dangerously close to the live experience.” JA was bothered by the difference between the left and right channels’ low-frequency linearity from the Low tap, and noted that the SE version measured no better than the standard VK-55. (Vol.28 No.11 Read Review Online; Vol.33 No.4 Read Review Online)

Conrad-Johnson LP125M monoblock: $10,000/pair
Like other C-J amps, the 125W LP125M has a 3⁄8"-thick, champagne-colored, anodized faceplate and a simple black tube cage for an elegant, utilitarian appearance. It uses one each 6922 and M8080 tube for the input stage, and two 6550 tubes in an ultralinear configuration for the output stage. Compared with Simaudio’s Moon Evolution W-7, the LP125M was softer on top, less powerful on bottom, and had a more laid-back sound overall, but nevertheless offered excellent dynamics and a more natural midrange, said RD. “Conrad-Johnson’s LP125 measures well for a traditional tube amplifier,” said JA. (Vol.34 No.12 Read Review Online)

Conrad-Johnson Classic 60 SE: $5000
See “Sam’s Space” in the April 2012 issue.

Fi 421A: $4575
Designed and built by Don Garber in Brooklyn, New York, the Fi 421A is a single-ended, capacitor-coupled, 4Wpc stereo amplifier with a single 421A power tube. It measures just 10" W by 8" H by 10.5" D, weighs 20 lbs, and uses high-quality parts throughout. The Fi sounded “open, clear, compelling, and lovely,” and had a knack for reproducing the human voice with outstanding presence and texture, said AD. Class A in special systems only, he cautions. Price increase since review due to new output transformers. (Vol.35 No.1 Read Review Online)

Luxman MQ-88: $8000
See “The Fifth Element” in the April 2012 issue.

McIntosh MC275: $4500 $$$ ✩
The revived 75Wpc MC275, preserves the look of the original while adding modern innovations. Chimneys are used to cool the tubes by convection, and three circuit boards have been replaced by a single board on which are mounted all components, tube sockets, and power-supply parts. ST: “I heard all the dynamic quality, all that aliveness of the original, plus a level of transparency that brings the MC275 definitely into the 21st century.” Sam bought the review sample. The fifth incarnation of the 75Wpc MC275, originally introduced in 1961, retains the first incarnation’s classic appearance and its use of four KT88 power-output tubes, three 12AX7 input tubes, and four 12AT7 driver tubes. New are a stainless-steel chassis, balanced inputs, and gold-plated, five-way binding posts. While the MC275’s two hefty transformers utilize the same “unity-couple circuit” invented by McIntosh in 1947, the copper wiring is now insulated in a more durable synthetic material. Though dynamic expression was restricted and bass notes were “a bit muddy” in dense musical passages, the MC275 produced “stunning” soundstage depth and “spooky” intertransient silences, said FK. Meanwhile, the MC275’s superb signal/noise ratios led JA to conclude that “Good audio engineering is timeless.” (Vol.27 No.7, Vol.33 No.10 Read Review Online)

Music Reference RM-200 Mk.II: $4800
Made in the US, the 100Wpc RM-200 Mk.II has the same basic physical and electrical architecture as the original, but uses better output transformers, adds a capacitor-forming function to extend tube life, and has a revised power supply. The fully balanced design features a high-power, bipolar, solid-state input stage and tubed driver and output stages. It uses two matched pairs of KT88 (standard) or 6550 (optional) output tubes, and a pair of 6BQ7 drivers. Though it lacked the slam and bass authority of more powerful solid-state amps, the RM-200 Mk.II produced airy highs, well-defined bass, and a lush midrange. “When the RM-200 Mk.II was in my system, I wanted for nothing,” said MF. JA noted “superb measured performance for a tubed design.” Hand-wound output transformers, add $1000; tube bias balance control, add $800. (Vol.34 No.12 Read Review Online)

Quicksilver Silver 88 monoblock: $4495/pair
Handmade and hardwired in the US, the Silver 88 is claimed to deliver 80W into 8 or 4 ohms. Refreshingly understated, with just a simple chrome chassis and carbide-black transformer cover, the Silver 88 uses a 12AX7 input tube, a 12BH7 driver, and two KT88 output tubes. Each amp has its own analog bias meter and a pair of trimpots behind each output tube for easy bias-current setting. ST noted tight, ample bass, stunning resolution, and lifelike harmonic presentation. “Instruments and vocalists had a realism that even the best solid-state amplifiers can’t seem to get right,” he said. (Vol.33 No.4)

Rogue Audio M-180 monoblock: $5795/pair
Built in the US, the rugged Rogue M-180 delivers 180W in ultralinear mode, and uses four Electro-Harmonix KT90 output tubes. Upgrades over the earlier M-150 include: increased power-supply storage; PRP resistors; Cardas binding posts, input wiring, and RCA jacks; improved input circuitry; HexFred high-speed diodes for the bias supply; and upgraded small-signal tubes. EL was most impressed by the Rogue’s ability to maintain articulation and propulsion while providing bass extension and weight. Compared to the Pass Labs XA30.5, the Rogue offered greater low-bass control and had a drier tonal balance. “A great value,” sums up EL. See also EL’s Rogue Atlas Magnum review in the April 2012 issue. (Vol.33 No.1 Read Review Online)

Shindo Cortese: $10,995 ✩
The 10Wpc Cortese is built around a Siemens F2a tube and uses the same tube-and-diode power supply as the Shindo Montille, but sends the output of the full-wave rectifier to a single large choke instead of two very small ones. It offered a sound “much bigger” than the Montille’s, with bass performance that was “quick, clear, and tuneful, with extraordinary depth and power.” In addition, the Cortese excelled at communicating both the meaning of the music and the emotional subtleties of a particular performance. “There was no sound that didn’t sound like music,” said AD. (Vol.30 No.7 Read Review Online)

Shindo Haut-Brion: $10,995
Like earlier models, the latest Haut-Brion uses two matched pairs of the rare 6L6GAY pentode tube to deliver 25Wpc. The output section is a fixed-bias design, with a regulated bias supply and individual adjustment pots for each of the four output tubes, while the output transformer is a C-core Lundahl model made exclusively for Shindo. Unlike earlier models, the new Haut-Brion has three 6AW8A triode/pentode tubes per channel, uses a pair of Alps 250k ohm potentiometers, and forgoes global feedback. Though it lacked some low-frequency tightness, the new Haut-Brion created an enormous soundstage and showed impressive force. “The amp was the pizzicato king,” said AD. (Vol.35 No.2 Read Review Online)

VTL MB-450 Series III Signature monoblock: $18,000/pair
Rated to deliver 425W (tetrode) or 225W (triode) into a 5 ohm load, the MB-450 III uses eight 6550 output tubes, a 12AT7 input tube, and a 12BH7 driver. Revisions to the Series II include a redesigned, fully balanced differential input stage, a lower-impedance output stage, premium Mundorf capacitors, and a shorter, faster, fully balanced negative-feedback loop. While the VTL sounded soft and “tubey” in triode mode, its tetrode performance was marked by an expansive top end, unusually fast attacks, clean decays, and well-controlled bass. “A significant evolutionary advance” over its predecessor, said MF. Because it provides lower distortion into higher impedances, the MB-450 III will sound best with higher-impedance speakers, JA advised. (Vol.34 No.4 Read Review Online)

B

Bryston 7B-SST2 monoblock: $10,200/pair
The superbly built 7B SST2 offers 600W in fully balanced, class-A/B operation into 8 ohms, and features a dual-mono bridged circuitry in which the two amplifier modules in each monoblock chassis are wired in series and driven by opposite-polarity signals. Changes from the original 7B SST include a circuit innovation said to maintain unvarying amounts of distortion throughout the audioband, new output devices, increased power-supply capacitance, a new low-noise power transformer, new computer-modeled heatsinks, more direct connections with less point-to-point wiring, and new cosmetics. Though the 7B SST2’s tonal balance was “essentially seamless and fully extended,” it lacked spatial depth and image specificity. When equipped with a new type of transformer trickled down from Bryston’s flagship 28B SST2 (serial number 001826 onward), the 7B SST2 produced tighter images, sharper transients, and improved bass definition. Nevertheless, when compared to the Class A Parasound Halo JC 1, the Bryston lacked bass control, low-level resolution, and microdynamic delicacy, said MF. (Vol.33 No.1 Read Review Online)

Moscode 402Au: $6495
Like its predecessor, the 401HR, George Kaye’s newest design is a tribute to the late Harvey Rosenberg. It marries a tube driver stage to a MOSFET power output and comes with pairs of 6H30Pi and 6GU7 dual-triode tubes, although many other small triodes can be used. Tubes are inserted into clearly labeled sockets behind a flip-down door of etched glass adorned with a glowing blue Moscode logo. Circuit-board traces are gold-plated, and the audio signal path is hand-wired with Cardas cable. The 402Au combined nuance with power, and was “superb at throwing its weight around.” Compared to the 401HR, the 402Au “had deeper bass, more high-end extension, and less grunge in the signal,” said WP. “It wasn’t just good. It was fun.” Must not be used with speakers having an impedance less than 4 ohms. (Vol.32 No.9 Read Review Online)

PrimaLuna DiaLogue Seven monoblock: $5495/pair
Offering 40W in triode mode (70W in ultralinear), the solidly built DiaLogue Seven boasts point-to-point wiring and PrimaLuna’s Adaptive AutoBias, the latter said to keep the output tubes operating within their best parameters at all times, for reductions in both distortion and tube wear. While the Prima­Luna’s sound in ultralinear mode was “stunningly dramatic,” “intensely involving,” and “consistently moving,” AD ultimately preferred listening in triode for its “less mechanical” sound. “An apparently reliable, obviously wonderful-sounding amp that offers higher-than-average value. . . . Very strongly recommended.” (Vol.32 No.12 Read Review Online)

Rogue Titan Atlas Magnum: $1895
See EL’s review in the April 2012 issue.

Shindo Montille: $4995 ✩ $$$
The 15Wpc push-pull Montille offers retro styling in a “determined-looking” steel chassis. Under its cover, AD found “superb craftsmanship” characterized by painted and polished surfaces, neat point-to-point wiring, and vintage American parts, including Allen-Bradley carbon-composition resistors and Sprague Orange Drop capacitors. With a “muscular but silky-smooth presentation” and an expert grasp of pitch relationships, the Montille followed music with “crazy ardor,” said AD. “Judged for its superior musicality, engaging sound, superb build quality, and the undeniable cool factor of a handmade, limited-edition amp, the Shindo Montille may be the most recommendable amp on earth,” he enthused. “Very high Class B!” (Vol.30 No.7 Read Review Online)

C

Z-Infinity Z40: $2999
Made in the US, the 20Wpc Z40 is a parallel single-ended amp with two EL34 tubes per channel in a fixed-bias circuit. Signal capacitors are all AuriCap polypropylene-film types; the input and output sections are hand-wired, point to point, with only minimal use of terminal strips; and the power supply is built onto a PCB of moderate size. The review sample’s construction quality was disappointing, with a number of messy solder joints, haphazard use of electrician’s tape, and loose reservoir capacitors. Nevertheless, the Z40 offered good tone and texture, solid bass, and excellent spatial performance, said AD. “A high-value product from a US firm worth watching,” he concluded. (Vol.35 No.3 Read Review Online)

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

K

darTZeel NHB 458, Simaudio Moon 880M, Anthem Statement M1.

Deletions

Conrad-Johnson LP66S discontinued; Chord SPM 650, Conrad-Johnson ET250S, Halcro Logic MC20, not auditioned in too long a time.