I've played for about half a year, about 5 shows a week, with a Mesa/Boogie Basis M-2000 and a Mesa/Boogie 2x10 cabinet. I'm very pleased with its tight, heavy, warm sound. One thing though. Sometimes, without an obvious pattern, it increases or decreases in volume on stage (I use it as a monitor). When I adjust the volume to the dB it had, I hear the PA getting too loud or too soft. This suggests that the amp is all right, but the cabinet fluctuates in volume. The guitar player of the band plays with Mesa/Boogie too, and he has exactly the same problem. Has anybody had experience with this, or know what to do?