If you do go for the Triple XXX you owe it to yourself to get some EL34's for it. I bought mine used and the guy already had a quartet of JJ's 34's in it. He sent me the stock 6L6's just for backup.
I played it for a couple of weeks and was just loving it. It sounds like a 5150 and a Dual Recto had an illegitimate love child. Yet there is this certain Marshally tone in there too, especially on the Crunch channel.
Anyway, after the first couple of weeks I decided to see what the 6L6's were like. YUKKKKKK!!!!! I was amazed at the difference. Quite frankly, had I heard the Triple XXX at a store with stock tubes I wouldn't have bought it. With the JJ's in the preamp and the JJ's 34's in the power this thing is way cool.
I bought it because I have been using my Vetta rig as my main and was starting to wonder if my previous tube snobbery was unjust. I found my Triple online for very cheap and figured I'd try it out. I knew I could get what I paid for it if I hated it so I went for it. The Vetta will be going up on Ebay soon. I still want a Mesa Mk IV but I think I'd keep the Triple too.