Boy, it's been a while since I've last posted here. Anyways, I've had an SWR SM-500 head with an SWR Goliath III cab that I've been using in a loud hard rock band. Recently... maybe the past month or so, I've been noticing that my head is clipping alot more than it used to. My settings havent changed at all (I have marks where my preferences are), but I have to keep the gain about an hour and a half less than normal. Just for reference, gain is at 8.5 out of 11 and master volume is at 9 out of 11. Normally I'm able to crank the gain to about 10 and ease off the master volume a bit, but now I'm compensating for loss in gain with the master volume, and that makes me nervous. Is it possible this is a tube problem? Thats all I can think of.