Haven't seen a mod forum for this amp. The special 6 and ultra forums have useful information. But this amp is its own beast. Got mine about a week ago. So far, I have changed the power tubes to el34s and also the preamps, tung Sol in v1 and eh's in the other slots. Changing the preamp tubes made a huge difference. Prior, the guitar was just way too boomy live. This was on my les Paul. Tele was unusable with the amp. Too bassy. Way too piercing. No mids at all. Now things are much smoother. Not so boomy. Actually have to increase the depth when I use the les Paul. What changes have other people made?