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.
One would presume a design flaw, I suffered with it for just under a month, I was happy to put it behind me as a failed experiment, too-good-to-be-true-I-shoulda-known-better, lately I'm trying not to resist my karma, which currently seems to be that whenever I try to go for a bargain or a shortcut it winds up costing me more in the long run to get what I want, puts a strange spin on the pursuit of the "sweet spot" that most of us here on the forums are trying to aim for.