I just bought a new MarkBass Jeff Berlin combo used it at two gigs. Volume was turn up maybe half. The amp did great know problems. Both gig's I got good feed back on how great my sound was. One gig was outside, but we were in the shade. 4 day's later I was playing in the house and thought I heard a popping and some popping when I turn a mid knob. But I'am not sure, but I payed a lot for it and only had it 25 days. Has anyone else had a problem like this with this amp. It hasn't happen again yet. I got this amp on sale at GC for $999.00 now they are back up to regular price.