Ditto to alot of this. I hit the preset and sometimes there is zero sound, other times the volume drops. Like others, I'll switch to another preset that works fine, come back to the one that malfunctioned and she's cranked again. No correlation between USB or not. Happens randomly connected or not. Weird and annoying but worse than that, gonna be REALLY embarrassing come solo time at a gig and i hit that baby only to hear nothing at all, or a volume that's way to low. Like others, I'll hit it twice and it usually cranks back up but not always. My unit is only 6 months old. I've resolved there will be no more updates/fixes so we'll just have to live with it and pray she doesn't go flat at a gig.