2015 Editors’ Choice: Power Amps $10,000 - $20,000

Equipment report
Solid-state power amplifiers,
Tubed power amplifiers
Aesthetix Atlas,
Air Tight ATM 300,
Classe Audio CA-M600,
Constellation Stereo 1.0,
Electrocompaniet AW180,
GamuT D200i,
Hegel Music Systems H30,
Jeff Rowland Design Model 625,
Pass Laboratories X350.5,
Triode Corporation TRX-M300,
Zanden Audio Systems 8120,
Zesto Audio Bia 120
2015 Editors’ Choice: Power Amps $10,000 - $20,000

Constellation Inspiration Stereo 1.0
The 200Wpc Inspiration Stereo 1.0 brings the same circuit design and some parts from Constellation’s $140k Hercules monoblocks to a more accessible price point. Constellation has done an amazing job of maintaining many of the qualities that made the Herculessuch a standout, including a highly resolved treble that never crosses over into the analytical. Transparency and timbres are also first-rate. The icing on the cake is that the Stereo 1.0 incorporates new circuit refinements that improve bass performance beyond that of its predecessors.

Air Tight ATM 300
The Air Tight ATM 300 is one of the handful of 300B SET amplifiers that lays claim to magical sound extending beyond the midrange. This amp’s airy highs, natural tonality, and lowbass extension defy common perceptions of 300B SETs. Scot Markwell.

Electrocompaniet AW180
The AW180 is a “tube-like” solid-state monoblock amp offering 180W into 8 ohms (considerably more into lower impedances). It provides very natural timbre and exceptionally realistic upper bass and lower midrange. Both low- and highlevel dynamic contrasts are excellent.

GamuT Audio D200i
This 200W solid-state amplifier has much of the liquidity, three-dimensionality, and image density of tubes as well as the expected virtues of solid-state: tonal consistency, frequency extension, and bass control. It runs relatively cool, is tonally neutral, and should be very reliable, producing a deep soundstage and enough power to drive most speakers well. Its only weakness is a tiny wisp of “fuzz” in the upper frequencies, noticeable only in a high-resolution system.

Zesto Audio Bia 120
Zesto’s new Bia 60Wpc, Class A, all‑tube power amplifier, with styling to match the company’s Leto linestage and Andros phonostage, brings the designers the trifecta. As with the preamps, Bia’s personality consists in a completely seductive musicality free from all the usual sorts of electronic colorations and artifacts, for a presentation that never, ever sounds electro‑mechanical, instead always wholly natural. Broadly neutral but not completely accurate, the sound here is more beautiful than real—luscious, velvety, silken, gorgeous.

Classé Audio CA-M600
Thanks to a highly sophisticated passive cooling system, the Classé monoblocks don’t run hot; nevertheless, their sheer dynamism and alacrity are stunning. Blinding speed is coupled to a spookily low noise floor. So linear and revealing are these amplifiers that in some systems they may best be coupled with tubes elsewhere in the audio chain. You can search far and wide for a better amplifier at double the price.

Triode Corporation TRX-M300
Think of the M300 as a modern version of the Western Electric WE 91A, complete with a 274B rectifier, a pair of 310A receiving pentodes, and a Psvane WE300B. Image solidity, according to DO, can only be described as magical; solid-state amps would kill for it. Bandwidth and transient speed are pretty impressive for an SET amplifier. Don’t expect bonecrushing bass slam, but prepare to be surprised by its dynamic prowess and the breathtaking acceleration of an orchestral crescendo from soft to loud. Speakers of 96dB+ sensitivity are advisable. TAS’ 2013 Low-Powered SET of the Year.

Hegel H30 Reference
This Norwegian powerhouse (375Wpc into 8 ohms) combines the bass control and dynamic impact of a dreadnought design with a midrange and treble refinement, delicacy, and sweetness reminiscent of a single-ended triode amplifier. The midrange, in particular, is highly vivid and present, with a palpability and directness of expression RH has not heard in an amplifier near the H30’s price.

Jeff Rowland Design Group Stereo 625
Jeff Rowland is back at the top of his form with this solid-state beauty, which is, as near as HP can tell, devoid of a solidstate signature. This gorgeous 300Wpc (into 8 ohms, 550Wpc into 4 ohms) Class AB stereo amp has wideband response with very low distortion, and a purity and sweetness rare in electronics of any kind.

Aesthetix Atlas
Aesthetix’s first foray into power amps is an unqualified success. Aesthetically, the Atlas is handsome in a brawny but tasteful way. Sonically, the amp has great resolution and reflexes, making it a snap to follow interleaved melodic and rhythmic lines. The Atlas creates a cloud of air around each instrument, and a deep convincing sense of space. Indeed, its resolution, timing, and imaging are beyond reproach.

Pass X350.5
The X350.5 has some marvelous qualities in an almost category confounding package: First, it has a great deal of the liquidity, warmth, and musicality of a good tube amp while also delivering the taut, defined, and stable bass usually associated with a good solid-state amp; second, it has much of the delicacy of a fine medium-powered amplifier but the power to drive just about any speaker; third, its asking price is considerably lower than what is often charged for similar performance; and fourth, it has an uncanny musicality that draws the listener into the human element of recordings and seemingly deflects critical analysis of any particular audiophile aspect. Co-winner of TAS’ 2013 Solid-State Amplifier of the Year Award.

The SA8 does have a sonic character—every audio component does. But like some of the best power amplifiers around, that character is exceptionally limited. In fact, almost all of the colorations you’ll hear through this amp are from the other components. In neutrality and transparency the AVM SA8 comes close to delivering the sonic equivalent of the Golden Mean. Its power is rated, with extreme conservatism, at 220 watts into 8 ohms, 450 watts into 4 ohms, and 650 watts into 2 ohms, meaning it can drive any realworld speaker load. It can also deliver an immense amount of current that will drive any loudspeaker. An exceptionally neutral and musical product.

Zanden Audio Systems Model 8120
$19,990 (optional balanced XLR inputs w/input transformers $1000)
For JV, this large, beautifully built-and-finished, KT120-tubebased, 100Wpc stereo amplifier from celebrated Japanese manufacturer Zanden is one of the great surprises of the audio season. Why a surprise? First, though scarcely inexpensive, it is considerably less money than Zanden’s typical gourmet-audio offerings. Second, though completely tube-powered and tube-rectified, it has none of the image blur, dynamic laxness, ambient grain, and timbral heaviness of typical Class AB KT-120-based push-pull tube amplifiers. On the contrary, it is exceedingly fast on transients, extremely hard-hitting on big dynamic swings, extraordinarily finely detailed, with taut bass, and imaging and staging that are truly wall-to-wall. One of JV’s references.