Components listed here have been formally reviewed in Stereophile and have been found to be among the best available in each of four or five quality classes. Whether a component is listed in Class A or Class E, we highly recommend its purchase.

Each listing-in alphabetical order within classes-is followed by a brief description of the product's sonic characteristics and a code indicating the Stereophile Volume and Issue in which that product's report appeared. Thus the May 2015 issue is indicated as "Vol.38 No.5."

In the 1952 edition of the Radiotron Designer's Handbook, long recognized as the "bible" of the industry, the permissible level of IM distortion for a high-fidelity amplifier was given as 3%, with the alternate figure of 2% being cited as a "rather extreme" specification. We wonder what the author of that statement would think of today's solid-state amplifiers with their measured IM of 0.01% and less. And we wonder what he would think about the fact that these super-amplifiers still have audible distortion.

There's virtue in being in the right place at the right time. The right place in this story was the headquarters of Acoustic Research in Boston, MA, and the right time was just a couple of weeks or so before the subject of this piece was to be shown (but not heard) at a press conference in New York. Even within that short two weeks, the rot started to set in. What I saw (and heard) in Boston on that occasion was a loudspeaker that stakes a reasonable claim on being revolutionary. A rare event that. The project name was The Magic Box and I was hoping that is what it might have been called when it went on sale. The Magic Box does, after all, conjure up an image of something a little special, and it's also easy to remember.

Imagine if you can a power amplifier with the bass richness, midrange liquidity, and high-end accuracy of the best tube amplifiers, and the inner detail, transient attack, and bass solidity and range of the best solid-state amplifiers. If you can imagine that, you can visualize what this amplifier sounds like.