Jiminy Xmas.
I keep looking at the UPA-2 longingly, but all these reports make me nervous. I'm also nervous about the heat generated by the thing, since it's an AB, not a class D. Someday, maybe, someone will make an affordable (read, ridiculously cheap) class D stereo amp not based on ICE. I'm looking at you, Ian.
emotiva has the same 30 day return policy as axiom so perhaps you'd like to give them a try. i own both a UPA-2 and a XPA-5 mind you they are currently driving 8 ohm loads but neither one of them gets hot, in fact after watchine avatar at a good volume (not ear bleed) the XPA-5 was only slightly warm. when i first got the UPA-2, i did a test and ran my fronts off of it for about an hour and it barley got warm.
again, this was with 8 ohm loads. when i get my new front 3 from axiom i'll see how the XPA-5 will handle the 4 ohm loads combo'ed with two 8 ohm loads for 5 speakers running on it. i'll be sure to let you know if i see a real noticable temperature rise or not. i should also state that both of my amps are completely out in the open with free air on all sides nothing stacked on them and they are not enclosed in any way. if that helps.
