@aberyclark
No, not really. The ONLY downside to class A amps is that they're obscenely inefficient and as a result make ungodly amounts of heat. Other than that they're technically superior in every way.
Transistors make a lot of garbage when you go switching them fully off. That's why you apply a little bit of bias to a class AB amp. Otherwise it's just 2 class B amps with a ton of distortion. Class D doesn't bias the transistors at all and switches them at very high frequencies and that creates huge amounts of noise and distortion. The output of a class D module then needs to be filtered extensively to block the huge amount of high frequency noise and smooth the notchy sort of output into something resembling a waveform.
The major advance in class D is stitching the transistors on and off even faster to achieve finer granularity in the pulsed output. That makes it easier to filter. Filtering isn't really advancing all that much. That technology has existed for a long time. It's just a debate of how to best apply it to this problem.
I, and many others, think simple, linear signal chains from the source to the speaker sound best. It's really hard to beat a class A amp with a nice, clean, low level, low and even order distortion character. That's very hard to do with class D.
