2015 Buyer’s Guide: Power Amplifiers $2,000 - $10,000

Equipment report
Solid-state power amplifiers,
Tubed power amplifiers
Aesthetix Atlas,
David Berning ZH-230,
MBL North America Corona C21,
Nuforce Reference 18 V3,
Sanders Sound Magtech,
Van Alstine FET Valve 600R
2015 Buyer’s Guide: Power Amplifiers $2,000 - $10,000

AVA FET Valve 600R
Frank Van Alstine’s 300Wpc hybrid amp is based on AVA’s patented forward-transimpedance design. A 12AT7 triode front end is coupled to a fully complementary power MOSFET output stage. The stock JJ Electronic tubes are quite musical, so there’s no compelling reason to tube roll. No, it doesn’t sound like a tube amplifier, but what sets it apart from a host of solid-state designs is its soulful midrange and ability to retrieve music’s drama and tension. Tack on decent spatial delineation and you have the making of a successful hybrid design. It’s a complete package featuring low distortion, superior speed, killer bass, and superb dynamics. The treble is somewhat closed in, and tonally, harmonic colors are on the dark side of reality, requiring careful system matching. At its best, the 600R can sound much like a $20k power amplifier. World-class power amplification at an affordable price. avahifi.com

Sanders Sound Magtech
This no-nonsense amplifier was designed to drive any loudspeaker impedance, particularly full-range electrostatics, which can have an impedance of less than 1 ohm in the top octave. The Magtech “sounds as if it had infinite power into anything with total stability,” said REG. The fully regulated power supply is unusual. Delivering 500W into 8 ohms and 900W into 4, and fully stable driving capacitive loads, it is the perfect choice for electrostatics. sanderssoundsystems.com

NuForce Reference 18 V3
We have reviewed successive generations of NuForce Reference 9-series Class D amplifiers, noting that each has offered worthwhile (albeit subtle) incremental improvements. With the Reference 18 V3, though, NuForce has taken a much more substantial sonic leap forward. Internally, the Ref 18 has a larger, more elaborate power supply than those used in past NuForce amps, necessitating a new full-width chassis. Sonically, the benefits are dramatic, including a more detailed, three-dimensional, and dynamically expressive sound than we’ve heard from past NuForce monoblocks. Although the Ref 18 has the same published output specifications as the Ref 9, it sounds noticeably more powerful and expressive. Similarly, low-level details and, especially, spatial/soundstaging cues flow more freely and effortlessly from the new amp. The upshot is that the Ref 18 is a forthright truth-teller that keeps faith with recordings, though it refuses to sweeten or embellish their sound in any way. nuforce.com

Aesthetix Atlas
Aesthetix’s first foray into power amps is an unqualified success. Aesthetically, the Atlas is handsome in a brawny but tasteful way. Its front panel offers a convenient menusystem for input selection and crossover point, the latter feature allowing the amp to easily mate with a subwoofer. 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. Tonally, this amp is on the sweet side in a way that is consonant with real music. The Atlas is slightly less incisive dynamically than AT’s reference amp, but so is pretty much everything else. Ultimately, the Atlas is a sheer joy—both sonically and musically—to listen to. musicalsurroundings.com

Berning ZH-230 ZOTL
ZOTL technology has been around for over a decade now. It represents David Berning’s approach to severing the Gordian Knot that is a conventional output transformer. The ZH- 230 is an update of the venerable ZH-270, albeit with lower power. Most notable changes: The RF carrier-frequency has been increased from 250 to 500kHz, and the source impedance has been reduced for increased damping factor. DO considers the ZH-230 to be a game-changer, in that it optimally combines the best of tube and transistor sound. Control of transient decay is exemplary, facilitating treble nuances that are silky smooth. The overall presentation is startlingly transparent and projects a refreshingly low-distortion signature. In other words, this is one sweet-sounding, smooth, and grain-free amplifier. davidberning.com

MBL Corona C21
Sounding more like a fine analog amp than the hybrid-switching amp it is, the 180Wpc C21 offers much of the lush sweetness and sonic gravity of MBL’s own Reference Line 9011 monoblock. It may not have the 9011’s slam, but in most other ways the C21 bears a strong resemblance to the flagship’s air and dynamic energy. Its top end, where Class D has previously struggled, is smooth and extended, not glassy. Its low end is elegantly controlled but not over-torqued. Rather it hasa bit of dark velvet bloom, imparting the full measure of harmonic and ambient decay and timbral resonance with acoustic music. This is an amp that can proudly stand next to the best in its class—switching or non-. mbl-northamerica.com