I finally had time to put 6v6's in my Club 40 and I think it sound pretty damn good. I used the Weber Biasrite and it was a breeze. I also picked up a Weber copper cap SS recto with no sag. I really like that as well it changes the attack of the amp as you would expect, a little tighter with no sag, obviously. The problem is that they all sound good! I think my favorite, at the moment, is the EL34's with the SS recto. But I'm gonna stick with the 6v6's for a while and take it on a few gigs and try to leave the Hot Plate at home. I know the amp can take a number of tubes but I think I'll stop here for now. This was also the first time I have looked inside the amp and wow, does Greg do a great job. Cool guy as well.