O.k, I need some of your brains. I just bought a brand new(possible floor model) Mesa 400+ and a brand new Ampeg 2x15 cab. I'm playing out of a Tobias (gibson) 4strg W/Bartolini humbucker. Th bass is setup for dropped A tuning (A,E,A,D) and I just spent $160 on some minor electronic repairs and a setup, just to be sure the bass wasn't the culprit here. That said, My rig sounds like SH@%. With the master on 7, the volume on 3, the EQ off, the EQ Knobs all at -5, 4ohm cab plugged into the 4ohm output, the bass an treble preamp on the bass barely over half and even the bass volume turned down a notch, the amp is breaking up (and by breaking up, I mean the most bowel destroying fart you've ever heard time's like...a million). My one guitar player has his triple rectifier stack on 3, and the other has his superlead 100 on 2. With my master on 7 and the volume on 6, the bass just starts to come through. I've tried every different combination of settings. High volume, low master. No EQ, Full EQ. My Guitar player is convinced the Mesa's are designed to only be played w/each other, i.e. mesa head=mesa cab. If you can offer any input or advice I will carry your child. Thanks.