...luckily I was able to go through the PA. I just came back from a gig where my Ampeg SVT III Pro basically died. I say "basically" because at first it wasn't giving me anything, then I would suddenly get some low-volume distorted sound, and then it would go clean before distorting again or cuting out completely. The amp has actually done this a bit before (fairly recently), but never to the point of not finally "settling in" and performing as it normally would. Does anyone have any idea what the problem could be (from my vague description). Could this be an issue with the tubes? The amp is around six years old and I've never had the tubes replaced. Thanks for any input you might have.