What is the best solid state amplifier you have ever heard?

Luxman 509X. Incredible. Do not WANT to hear the M-900U/C-900U which is the Luxman combo that is appreciably better than the 509X. Supposedly the 509X is 90% of this top combo;

The engineering that went into the 509X receives maximum applause from me. 

+1 millercarbon

Someone posted a thread titled the best sounding integrated you’ve ever heard and akg_ca was somehow able to provide an answer, sans the unnecessary diatribe.

Best solid state amp I’ve heard was a Goldmund.

Luxman m900u is my favorite so far and one I hope to get in 6 months. 

second on the M-900u over Dag S250 which i recently owned. tube was Ref 75se. the luxman was superior to the other two imho but would be extremely happy with any of them

Pure SS Musical Fidelity AMS 100
Ayre VX-R Twenty
Vandersteen HPA-5 if you have powered sub or steens

but as Beetlemania said you should consider hybrid like Aesthetix and IF you have powered sub the Vandersteen HPA-7
just 5 parts in signal path, liquid cooling for perfect bias, no emitter resistors, floating ground, built in HRS isolation, the list goes on.....