My vote is for the Audio Research Reference 10 preamp which works extremely well with any solid state power amplifiers (the best of both world)...I have personally compared all three preamplifiers in my system and ended up with the Audio Research. The Ref 10 is the end game preamplifier...and it is so much fun to own especially when you could roll some tubes and get a different taste!
Audio Research Ref 10 vs 40th Anniversary preamp
I was wondering what the difference in the sound between the Ref 10 and the 40th ? Not much wrote about that. I btw have the Ref 6 but never heard the 10 or the 40th.