Yep, a couple surprisingly serious issues on these amps - the lack of regulator de-rating (and hence dying) on the effects/preamp board and the over sensitivity to dirty power (which is everywhere).  If the black boxes is the regulator thing, your direct out will die as the direct out comes off the preamp board.  A ~$10 part plus heatsink and an hour of technician time should make it better than new.  Only thing we can do for the over sensativity to line power is to lug around a voltage stabilizer.

I've only had the amp cut out on me once (on an oncore no less...), but suspect it was the power - been using a voltage stabilizer since and it hasn't happenned again.  If that regulator ever goes on mine, I'll replace it with a beefier one and install a heat sink.  I did some looking but couldn't find it - maybe someone else here can - but someone actually did a little write-up on here with pics on replacing the voltage regulator.  If you take it to a shop, I' d print that out and take it with.