tonight i was playing my swr bass 350 at the volume i always do. no clip led light or anything. my amp wasn't overly hot, it was pretty darn warm but not the searing heat it usually gets after a set. well the amp just shut off mid song. i checked the amp and speaker fuses but they were intact. nothing else in my rack shut off. it wouldn't turn back on for at least 15 minutes and then finally it did. it was really noisy for a while too. i had the levels i was playing at when it shut down and banged the bejesus out of the strings and there was still no clip led flashing. i know it wasn't the fuses, i know it wasn't clipping, and it wasn't overheating i don't think. could it be the preamp tube going? i don't know... any thought or ideas would be greatly appreciated, thanks!