Ive had SS and tube class A (last one with 300B tubes) and now I have the Nord Acoustics NC500DM class D amp with Rev D boards and Sparkos Op Amps and I prefer it over all of my previous amps. Its cristal clear, with amazing dynamics, incredible soundstage and neutral tone. My previous class A amps sounded "dirtier" to me.
I think that when you have a considerable transparent amp (as speakers), it will show the flaws of your source. The more I improved the quality of the source (AC Power, digital signal processing, cables, DAC, etc) the warmer the amp got.
I've heard +100k systems with class A and AB systems that, to me, sounded harsher (and worse) than my current around 20k system.