I wrote:
" I have no doubts that they (class D amps) posses the maximum ratio performance/sound quality among the amplifiers of all classes",
whereas I meant that class D amplifiers give the maximum ratio
performance/price, among all classes of amplifiers, where
performance = sound quality. Or more widely, we may let
performance = (sound quality - weight - size - energy consumption).
Indeed, i think that Class D amplifiers are unbeatable in this issue and, very unlikely, this can be changed in the future. Hooking up for the first time my $1500 class D amp to my system, i was sincerely surprised how one can get that quality of sound for that money!
At the same time, i think Class D is still under the basic development process (e.g. @yyzsantabarbara has posted a website speaking about recent developments in PURIFI Audio).
I share (a common?) opinion that class D amplifiers give a clear transparent sound with details and resolution. True, but something is missing. The fact that sound is transparent does not mean that it is warm and live. Take a frozen or a wax figure. It is clear, transparent, even more bright than a human, but you can see that it is not a human - the spirit is missing. Likewise, Class D gives a detailed, bright sound, though some warmness is perhaps missing.
It is possible that there are class D amps, that i have never auditioned,
sound non-wax and warm (many of you mention Nord Acoustics amplifiers). But it turned out that one I have, PS Audio Stellar S300, an ICEpower model, should be one of the warmest sounding class D amps (so i am lucky!). Athough i can still enjoy it, not to the same extent. I share what George says in points 1 and 2. I do not think these are technical issues, rather they come from the auditioning experience. The tweeter damage issue, i think, should not be typical for any class D amp -- perhaps, this particular case was provoked by some wrong current or a defect of fabrication or the amp or/and CD.
Thanks @golfnutz for your notes on Red Dragon S500 with Thiel CS3.6 that i bear in mind (I also own CS6s, both are excellent speakers, CS6s sound a bit more real though).
I see Class D, being an ongoing development (carried out by the scientists), as the future of the amplifiers. Already today (unlike electric autos vs gasoline ones), Class D amps are considerably cheaper than Class A, AB amplifiers. They are much lighter, smaller, do not get hot and consume little energy. With all of this, the sound quality that they give is not that bad at all, and, i think, it will become better in the future. I think this development deserves a 100% support from all of us.
Cheers,
Nodari