I run my Wadia 850 into a Pass Labs X1 (solid state) preamp. This preamp is very transparent, and adds no euphonic coloration either yin or yang. IMO it gives body and dynamics to the music that I don't get when running directly into an amp. In my system I've also had an ARC LS25 (nice but too "tubey") and the Levinson 380S (left me uninvolved). I suppose TOP-end preamps, whether SS or tube, would be the way to go here (e.g., Levinson #32, ARC Ref2), but I could only afford the Pass for now. You might also want to check out the Sim P5 if you're in the "moderate" price range.