Solid State Power Amp Reviews

As I write this, in early August, the global economy is in flux and the stock market gyrates, seeming in stark contrast with the gleaming, luxurious audio components that surround me. Perhaps there is some prescience in my rising interest in reasonably priced, high-performance products, as exemplified by the Oppo Digital BDP-95 universal Blu-ray player, which I reviewed in this column in September. Surely there must be other products that provide truly excellent sound at prices strikingly lower than expected.

Power amplifiers are unglamorous but essential. In theory, they have only one task. But, according to audio sage Yogi Berra, "in theory, theory and practice are the same. In practice, they are not." Amplifiers must take a voltage input signal and provide an output of somewhat higher voltage but of substantially higher current, the product of which is power. The task is complex in that this output must be applied to electrical interfaces whose characteristics vary widely from speaker to speaker—across the audioband and, for some, even at different power levels. There are no control mechanisms or feedback signals to help. The power amp must just stand and deliver.

The power-amp saga continues. For months, I've been plowing through the market, searching for something to drive my three front speakers. (I use a two-channel amp for the surrounds.) It can be a three-channel amp or three monoblocks—it just has to sound great with my speakers, and be light enough that I can lift it by myself when I need to rearrange my system. I'd finally settled on Classé's Sigma Monos for their transparency, and because I can manage their weight, one at a time. At the CEDIA Expo in September 2016, I saw two more candidates worthy of consideration. Review samples of both arrived here almost simultaneously.

Sometime near the turn of this century, I wandered into a demo room at a Consumer Electronics Show and discovered, in the exhibit of a company I'd never heard of, an integrated amplifier that sounded clean and refreshing. It was the only product Hegel Music Systems displayed at that CES, and I don't recall its name or the associated equipment, but I've always remembered that model's striking appearance and impressive sound quality.

How much amplifier power do you need? Most audiophiles figure a maximum of a few hundred watts per channel—beyond that, you're wasting your money or showing off. Others think that anything more than a few watts will mess up an amplifier's musical coherence or "purity," so they stop there and find uncommonly sensitive speakers, usually compression horns with cone woofers.

"That's just silly on so many counts, Antony."

I was talking last winter to Musical Fidelity's Antony Michaelson, who had been enthusing about his forthcoming stereo amplifier, the AMS100. It would be physically enormous—almost a yard deep—and commensurately heavy at 220 lbs. Despite its bulk, its maximum rated output would be just 100Wpc into 8 ohms. It would also be expensive, at $19,999. And to cock a snoot at environmentalists and their concerns, the AMS100's output stage would be biased into class-A up to its rated 8 ohm power, meaning that, even when not playing music, it will draw around 10 amps from a typical US wall supply of 120V. This also means that it will run very hot, making the amplifier impracticable for summer use in homes without central air-conditioning. Like mine.

Not every audiophile needs an amplifier powerful enough to tax a small town's power grid while simultaneously draining his or her bank account. So, having quickly sold out of its ultra-limited-edition, extravagantly powered and priced combo of kWp preamplifier ($14,995) and kW power amp ($27,995) that I reviewed">http://www.stereophile.com/tubepoweramps/104mf">reviewed in January 2004, Musical Fidelity (footnote 1) set about capitalizing on the enthusiastic reviews earned by those giants with less expensive, less powerful, "real-world" replacements.