Checked with Audiosource, there is no manufacturer warranty on these amps, and buy.com won't allow returns on this item... That's too bad, running one bridged on each front channel would be pretty sweet for music. However, I don't think this would make a good sub amp... I don't think it'd be powerful enough, there's no low pass x-over, rumble filter, phase switch or equalizer.
It's a nice audio deal, I'd jump on it if they 30 day returns or if I could afford to take the chance.