Funny, I haven't read anyone comment about having owned both class d and a-a/b. I'm very interested in what they think. This thread, as well as the entire audiogon forum, is populated with either/or, one or the other, with very strong advocates in both camps.I haven't been paying close attention to this thread, so perhaps someone has already responded in a similar way.
I've owned many amps that use differing underlying technology. I'm including integrated amps in the lists below.
For class A/B I've owned the following brands - Rotel, Parasound, Krell, Lexicon, Marantz, and Emotiva.
For class D I've owned the following brands - Wyred 4 Sound, Peachtree, and Sunfire.
For tubed amps I've owned Rogue Audio and Audio Research.
I recently purchased a Heed Elixir integrated that uses what Heed calls "Transcap" technology.
I have not owned any pure Class A amps.
I think they all have strengths and weaknesses and what really matters at the end of the day is how they sound. A lot is going to depend on the way the designer understands and implementsed the technology and the level of the build quality and components.
Out of all the amps I've listed, the ones that I have liked best (and still have) are the Rogue Audio M-180 tube monoblocks, the Wyred 4 Sound Class D ST-1000 MKII, the Audio Research tube VSi-55 integrated, and the Heed Elixir integrated.
It's hard to imagine the entire market going in one direction or another. Designers may be more knowledgeable about a specific type of technology or prefer the way it sounds and so it seems logical there will continue to be diversity among design and implementation philosophies.
Vive la différence!