Replacing the preamp tubes is a good idea. It made a huge difference in mine. It came with some cheap sh*t
Chinese tubes.
A buddy of mine here has a set of "tester" tubes that they test out amps with. They were a set of Ruby Tubes (made my JJ Electronic, what I wanted anyway) that he let me take home. I put them in and wow, what an immediate difference! The power tubes were my favorite, Svetlana EL34's, so I didn't replace those just yet (although I did find a new set so I bought them to have a backup). Svet's are great and tough to come by at times, hang on to'em until they start to really just sound bad.
Good luck.
Oh btw, here's my exact settings for Channel 1:
PCOMP - 8, pushed in (active), set to Channel 1 only
Volume - 6
Bass - 7.5, pulled out (Gain 2 active)
Slope - 2
Middle - 4.5, pushed in (passive notch shift)
Treble - 6, pulled out (Gain 3 active)
Master - ? hehe, I usually play at about 1.5 just in the house.
Focus - 10
Presence - 7.5
Hope that helps you some.
