Our band usually rehearses about 2 - 2.5 hours straight. I seem to have intermittent problem whereby a note will honk sounding like only the horn/tweeter in my cabs made the note or one very distorted note, then the next note resumes the normal sounds until the next honk 10-20 minutes later? Has anyone else come across this issue? As the amp is still under warranty, I've put it in and the first testing by the tech yielded the amp sounding great. I've pressed to have this looked at by their service department but expect the same result will occur. The MB500 will send 250 watts to two 400 W rated cabs - a GK410 SBX and a Neo 115. Admittedly, I have the master at 3:00 o'clock and the gain at 1:00 o'clock. At these volumes, I have the amp's limiter engaged and I'm using a BOSS LMB-3 as a compressor/limiter. I have the low-mid set around 2:30 and the bass around 9:00. The techs have suggested it may be the speakers reaching some sort of limit. Anyone have a similar issue at similar volumes and/or any advice/insight would be appreciated.