We all have biases. The trick is knowing your biases so they don't get in your way. Mine are pretty obvious. I don't like "fussy" gear that demands special care and feeding. I'm lazy—I want to just turn stuff on and begin listening. Perhaps that's why I have a positive bias toward Nelson Pass's designs. They're reliable, untweaky, and usually sound good.
To high-end audiophiles, the Boulder 500 amplifier and its less expensive derivative, the 500AE (Audiophile Edition), would not seem to be "high-end" designs. They are designed around op-amps (felt by many to be generally poor-sounding), they have scads of negative feedback (which is perhaps why op-amps sound bad), and they have only a moderately hefty power supply. Why, then, is Stereophile publishing a review of an op-amp–based power amplifier? Read on...
I think every audio reviewer hopes for a surprise—when a good, but not outstanding, product is refined by the manufacturer into something special. The review then becomes an exciting discovery, reaffirming the pleasure one takes in good audio, and in listening to music being reproduced as it should be. It makes the listening exciting and the writing easier. The Classé Fifteen solid-state stereo amplifier is just such a surprise.
It was a hot, humid, New York City evening in early August, and I was thankful to be sitting in the air-conditioned dark of Avery Fisher Hall, up in the Second Tier, for a Mostly Mozart concert. Listening to cello soloist Alisa Weilerstein in Osvaldo Golijov's hypnotic Azul, I was suddenly jolted by an explosive mix of primitive cello sonorities, accordion, and staccato riffs on ethnic percussion instruments. My thoughts turned to the importance in music of both power and delicacy, and of how Bryston Ltd.'s 28B-SST, a 1000W monoblock power amplifier, was designed to address both.
Boulder Amplifiers, named after the Colorado town where the company has resided since its founding 23 years ago, makes some of the most elegant-looking solid-state amps around. Chassis are anodized, aircraft-grade aluminum with rounded edges, machined and finished in-house. The two models reviewed here, the 810 line preamplifier and the 860 power amplifier, each have a sleek, compact build—stacked atop each other, the two stand just over a foot high—owing to extremely efficient packing of the circuitry inside. These are the company's "entry-level" electronics, but there's nothing cheap about them—the preamp retails for $6900, the amp for $8500—and for all their economical size, they look like luxury goods as well.
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.
There's always a certain amount of jockeying for position at the very top of the High End. Every few months, a new star burns brightly, getting all the attention. While the constant turnover at the cutting edge helps to define the state of the art, audiophiles should keep their eyes on the longer term. It's a company's track record—examined over a period of years—which defines its position in the market and the credibility of its products.
Some readers may feel that it is pushing poetic license beyond reasonable limits to call the Krell KSA-50 a "new-wave" amplifier. It has, after all, been around for several years. The Krell KSA-50 is new-wave enough, however, to be an incredibly stiff class-A design, rather than a pseudo–class-A circuit, and its 50 watts per channel are supported by enough of a power supply to drive an arc welder. You get about 70 watts of RMS power with 8 ohms, 150 watts with 4 ohms, and sufficient watts into 2 ohms to threaten my load resistors. There is almost enough power to drive a pair of Apogee Scintillas at their ohm setting—though I'd prefer at least the Krell KSA-100.
I still have fond memories of my first Krell amplifier, a KSA-50. Back in those days (date purposely omitted), my principal source of audio equipment reviews, aside from Stereophile and The Absolute Sound, was Hi-Fi News & Record Review, which I read voraciously from cover to cover every month. One fateful day while sitting by our community swimming pool, I happened upon an enlightening review of the KSA-50 written by none other than our own John Atkinson, editor of HFN/RRat the time. His words describing "the steamroller-like inevitability of the bass with this amplifier" haunted me for weeks, until I got up the nerve to audition, and ultimately purchase, my first Krell product.
"A high-quality amplifier must be capable of passing rigid laboratory measurements, meet all listening requirements, and be simple and straightforward in design in the interest of minimizing performance degradation..."—Cdr. Charles W. Harrison Jr., Audio, January 1956 (footnote 1)
Rumor had it that if the MF2500 amplifier had gotten any better in development, Conrad-Johnson would have had to include it in their "Premier" series. However, C-J's intention was to hold to the lower price of their established MF series, and so they have. Rated at 240Wpc and retailing for $3495, the '2500 is the core model of Conrad-Johnson's current range of "MF" power amplifiers. Its companion MF2250 offers 120Wpc, while the MF5600 delivers 120Wx5 for multichannel home-theater applications.
Good things come in threes, they say. Well, three-channel power amps suit me just fine. My main component rack is at the back of the room, so I split power duties between a two-channel amp under the rack to drive my rear-channel B&W 804S speakers and, way at the front, either three monoblocks or a three-channel amp for the front three B&W 802Ds. I do this to ensure that the timbre of the front three channels is consistent. The outstanding performance of the Simaudio Moon W-8 dual-mono power amp (Stereophile, March 2006) almost tempted me to go with a stereo amp and a monoblock, but voicing and balancing a multichannel system with equanimity makes me want as much simplicity as possible. I guess manufacturers and users see it the same way; many new three-channel amps are coming on the market.