Quote Originally Posted by tonebender View Post
I always run 12AT7's in the V1 slot, especially an amps 20W or less. It seems to give me more clean headroom. Don't know why, read it somewhere, tried it and it works for me. As for the other slots, I've never experimented or heard anything about changing the type from what comes stock. I usually do try to upgrade all tubes from Chinese to better tubes. Hope this helps.
Eurotubes had recommended a 5751 for the same purpose. Someone else on The Gear Page had put a 12DW7 to accomplish the same thing. Apparently that tube is half 12AX7 and half 12AU7. Might be an interesting thing to try since there isn't a ton of clean headroom on it to begin with. Of course, that's not the point of this amph in the first place.