I know you said Tube Amp, and I agree, but look intoa little gem called "Lab Series." It was designed by Moog and Gibson used them. Made in the US up by Chicago. I had an L4 and it was stolen

amazing on guitar or bass and you can get them at a really decent price (I don't think I've seen one go over $300 ever). The con is that they're solid state, but man, what an amp!
scott