When all you've ever heard are wooden boxes that shout, it's difficult to recognize their highly accented "voice." Few of us actually notice how miserably distorted all loudspeakers are. Don't believe me? Try listening to a recording of your child's voice, the sounds of rattling keys, or an audience applauding.

Of the hundreds of product reviews I have written over the years, it is perhaps those of power amplifiers that present the hardest task in defining their worth. This is not because power amps are unimportant. As I wrote in my review of the MBL Corona C15 monoblock, in June 2014, "it is the power amplifier that is responsible for determining the character of the system's sound, because it is the amplifier that must directly interface with the loudspeakers. The relationship between amplifier and loudspeaker is complex, and the nature of that relationship literally sets the tone of the sound quality." But because the amplifier's role is so fundamental, it can at first be difficult to determine a given amp's balance of virtues and failings. A paradox.