I have a Shindo preamp into Quicksilver V4 monos(170w into 8 & 4 ohms w/kt150s). Went to a difficult stand speaker, 85 dB, 4 ohm dipping down to 3.2, ouch! Tried class D power amps because of the drip in impedance, base got faster but everything else, (ie, what I call tube magic) was lost.
Class D has its place in my opinion, just not in a critical listening environment when the life of the music is most important.