So last night I was playing at a club and I was getting an intermittant volume drop. Every few minutes I'd loose volume (I could still hear a little sound coming out of my cabinet). During the second set, it happended around 6 six times. During the last set it happened a couple of times. Here's what I was using: Mesa M-Pulse 600 (new, only used 4 times) SWR Jr Golliath 210 Carvin 4 string with pre-amp Theories anyone?? Bad Cables? Pre-amp tubes? (checked 'em...they look ok) 9v battery in bass? More serious amp issue? Help?