I purchased a 5-6 year old MB amp about 2 years ago. I think my tubes need replacing, because my overhead seems to be getting lower. Channel 1 is pretty weak, Channel 2 is better, but doesn't seem to have the thump it once did. I am running it 4homs into an AccuGroove El Whappo cab. Does anyone have experience in different tubes with this head and what a good replacement might be? Thanks!
