That sucks, how long did you have it, wasn't it still under warranty? This is just my opinion, but there is no reason an amp like that with those specs, should even break a sweat driving the 80's, something is just wrong.
I think I had my MPS-1 for almost 3 months with all the back/forth trial and error to resolve the issue, they agreed to give me a full refund. Sorry for your troubles.