Funny,...... The first thing I thought of when I saw the title of the thread pop up was, "Oh, there's another DSL401 with a bad bridge rectifier". Besides bad tubes, it's really about the only thing I've seen go wrong with these amps. It's a relatively common problem. That said, every amp is different and your symptom could certainly be caused by some other problem, especially given that we don't even know what the symptom(s) are. If it is the BR, I'd replace it with a higher current version and/or add a heat sink and leave the leads long enough to stand off the board a bit.