Ya, that makes a large difference for sure. Although the previous version didn't have any trouble with it. I generally like the bright switch on on most amps as I find it gets things more articulate. Also, other amps do not present this same whistle regardless of master volume or bright switch. It's important to note that the whistle is NOT feedback from the guitar or speakers. I can have my speakers entirely off and record the same sound. If it's something to do with the topology of the amp and can't be remedied, I'll be a little bummed out. Otherwise I wouldn't continue this thread. haha