When thermionic tubes ruled the audio arena and solid state amplifiers were introduced with its first offings in the early 1960s, there was great controversy and skepticism about the "new technology". Solid state amplifiers have been with us for about 40 years and it is interesting to note that today class A/B technology appears to be the most common and widely used means of audio amplification, with class A tube enthusiasts in the minority (though there appears to be a resurgence of interest). Then came class D technology. Again, the shroud of controversy and skepticism surrounding class D technology sounds like deja vu, and the debate of yore that seemed so heated between tubes and solid state!
Here is an excerpt from Stereophile's archives
http://www.stereophile.com/historical/565may/ with John Atkinson's editorial note and J. Gordon Holt's article of 1965:
Stereophile Editor's Note: "Those of us who cut our engineering teeth on tubes still remember the advent of the solid-state amplifier with mixed feelings. Yes, they were lighter and cheaper per watt than the thermionic hulks we loved so much, but they broke all the time (thanks to the germanium transistor) and sounded like—well, let J. Gordon Holt tell us what they sounded like in an "As We See It" article from Vol.1 No.10, first published in May 1965. We also develop the theme with a JGH review of an early transistorized amp, as well as a selection of readers' letters from the early days of Stereophile. Enjoy."—John Atkinson
Do read the article from start to finish, as well as the link at the bottom of the page [Article Continues: KLH Model 16 amplifier]and the Readers' letters that followed. If we substituted the phrases "tube" and "solid state" (or its derivative) with "solid state" and "class D" (or its derivative), respectively, there is an uncanny similarity with the debate today with class D amplifiers in general, and TAS's lukewarm reception in particular.
I would like end with a quote from J Gordon Holt, made with reference to the tube v solid state debate, but which I think also is the reason why there is so much skepticism with class D technology:
"The point in question is not one of potential quality, but of quality that has been available to date in commercial designs."
Class D has great potential to excel, and some of the designs that are at the cutting edge of technology, specifically addressing and successfully eliminating such issues as RFI, are already in place. I foresee that class D technology will continue to progress, with more and more amplifiers (including some sacred cows) embracing the new technology. I would like to see three streams running parallel with each other, respecting each of the technologies, but offering the consumer greater choices, and with it the ultimate of musical enjoyment! It is great to be an audiophile consumer in these new times!
Dennis
