i have heard excellent class D amplification. stunning with the right music and recordings.
for me it has one fatal flaw, an inability to handle compressed music and music with intentional distortion, e.g. arcade fire, sonic youth, flaming lips, spoon, tame impala.
there is an additive distortion effect to this music that makes it intolerable to my ears. tube amps handle it ok, class ab a little worse but class d not happening.
This is the heart of the problem with Class D, in a nutshell.
100% of the music, for the human ear, lies in the proper placement and expression of micro detail, in time, in living breathing relation to all bits of said micro detail, in time and levels (micro and macro levels in micro and macro time..)(the ear/brain is the world's finest FFT system and varies in quality and effectiveness from person to person)
This is the part that Digital and Class D get wrong. It’s intrinsic to the technology of both. Core.
Their ’residual’ distortions are right in the heart of how the human ear/brain functions and listens. 100% of how the ear/brain works, is squarely in the sights of how and where in the signal -that these technologies distort.
Therefore, to the discerning ear and mind, both are a failure.
Listenable? Sure. For some of us, if we grunt and ignore our natural tendencies in how we listen.
Best? Very much a no.
I’ve said this, now, maybe a good few dozen times on this forum and human ignorance and projections says I’ll probably have to say it forever. That it will outlast me and wear me down. Where this norm of the human condition really will manage to eventually...cut down trees with herrings. Forever. Until humans evolve into something else with a different set of cognitive problems. Plenty more where that came from...