Solid State Power Amp Reviews

When Michael McCormick, president of Bel Canto Design, suggested that I review their Black ACI 600 integrated amplifier, I accepted without hesitation. As wonderful as my reference system may sound, its dCS digital front end alone comprises four boxes and a web of cables complex enough to send many a spider spinning. Given the choice between connecting that front end to a pair of expensive, enormous monoblocks—with their similarly expensive AC cords and equipment racks/isolation platforms—or to a single, visually elegant, 45-lb box that costs $25,000, produces 300Wpc into 8 ohms, and requires only a single power cord and shelf, I think many an audiophile, even those with lots of money, might gravitate toward the latter.

The XA25 stereo amplifier is the latest addition to Pass Laboratories' XA series of amplifiers and, at $4900, the lowest priced. It weighs only 45 lbs, has single-ended inputs only, and outputs 25Wpc into 8 ohms, 50Wpc into 4 ohms, or 100Wpc (!) into 2 ohms. According the XA25's well-written owner's manual, it will deliver 50W peaks into 2, 4, or 8 ohms—in class-A.

Although PS Audio's Stellar M700 monoblock power amplifier ($2998/pair) is a brand-new design from a team led by engineer Darren Myers, it draws on the company's extensive experience with class-D amplification. Sam Tellig and Kalman Rubinson reviewed PSA's HCA-2 power amp in, respectively, the October and December 2002 issues, and I reviewed their GCC-100 integrated amp in January 2006. The Stellar M700's input stage is the latest version of PS Audio's Gain Cell, which they describe as a "proprietary, fully differential, zero feedback, discrete, class-A MOSFET circuit.

For as long as I've known about high-end audio, I've put Dan D'Agostino, co-founder of Krell, on the same pedestal reserved for the likes of Frank McIntosh, Saul Marantz, Avery Fisher, H.H. Scott, and Sidney Harman. The reason is simple: Dan's the man whose achievements at Krell led me from the harsh sound of my first high-end amp into another dimension, one of truly musical sound reproduction.

There seems to be an inexhaustible supply of amplifiers; it's hard to choose which ones to review. Big-name operators are difficult to ignore, while smaller outfits often complain of neglect. In the case of a new and moderately priced introduction from Krell there's no need to find excuses: it's available, it's likely to be important judging from this company's track record, and we'd all like to see just how well it performs.

This review features the KST-100 stereo power amplifier. Initially this product was differentiated from the more expensive Krell components by having an all-black livery. However, as customers showed a preference for Krell's traditional anthracite finish, the KS series is now also available in this finish.

Dinesh Paliwal, CEO of Harman International Industries, was addressing engineers and the audio press in a crowded conference room at the opening of Harman Luxury Audio's new Engineering Center of Excellence (ECOE), in Shelton, Connecticut. Paliwal singled out as the ECOE's first beneficiary the Mark Levinson brand, with the goal of revitalizing it as Harman's flagship marque. (Other brands in the HII stable include Harman Kardon, Infinity, JBL, Crown, AKG, Lexicon, and Revel.) To achieve this, he gave the ECOE team access to Harman's R&D budget of $400 million; brought on Todd Eichenbaum, formerly of Krell, to be its Director; and hired 11 more engineers.

Three years ago, when I first heard Audionet's Max monoblock power amplifiers, I described their pairing with YG Acoustics Hailey loudspeakers "an absolute winner" and "definitely one of the finer systems at T.H.E. Show Newport Beach." At subsequent audio shows, no fewer than four other Stereophile Contributing Editors enthused about different pairings of YG loudspeakers with Audionet amplification. Herb Reichert, at the 2014 Rocky Mountain Audio Fest: "Everything had a kind of just right quality. Totally impressive!" Sasha Matson, at RMAF 2015: "Marvelous" on vocals, "rockin' and tight" on bass and drums. John Atkinson, at T.H.E. Show 2016: "Duke Ellington's classic Jazz Party in Stereo . . . was reproduced with terrific dynamics." Larry Greenhill at the 2017 Consumer Electronics Show on the sound in the YG Acoustics room, which included Audionet's Max monoblocks: "the sound on playback of Jake Shimabukuro's ukulele wizardry came closer to matching his live performance than in most rooms."