From my experience, matchining a good tube preamp with better class D amps produces the 'best' sound, imho....when you are using a class D amp.
Ice Block Amps
I just purchased and received 2 mono block, Ice Block amps from Seymour Audio. I'm a Cary tube person so this was a stretch for me. Running these through my Cary SLP-05 preamp was just unbelievable. The sound, build quality and price blows me away. I've done lots of SS and tube but this one is unbelievable. I'm not connected to these people in any way.