How big of a difference do amps make?

I agree with Schubert. Tube amp with SS pre is better than SS amp with tube pre. I tried it. All tubes is the best. I have Lipinski L707 speakers and they sound great with my Linn Classik, but not nearly the same as my Cary tube set up.

The tube amp makes a huge difference, the preamp second.

McPherson, yes, without question. I went from a Carver M 1.5t amp Carver C-1 preamp to a McIntosh 7270 SS amp to the Carver C-1 pre then tried both amps hooked up to my current Cary SLP98P tube pre. The pre made a difference with the SS amps and so did the amps, then I hooked up a Cary V12R tube amp to the Cary tube pre, and heard a big difference, and an even bigger difference when I hooked up my current Cary CAD120's tube amp. Thursday, I'll be getting some (8) matched Gold Lion KT-88 tubes to find out if they will make a difference instead of the stock Electro-Harmonic's.

I'd trade my beloved tube pre to a SS before I'd ever trade my tube amp. However, it's nice to have both.

You'll get better seperation with mono's too. If you keep the Thors, get a new set of tubes plus a couple of extras for back up and you should be set for a while.