I think the problem with your 15-volt, 800ma power supply for a pair of multimedia speakers is that the empeg draws a peak of 8.75 watts.

Actually, the 800ma one is the one that's working fine. It was another 15v 450ma power supply that wouldn't cut it. Like I said, I was scrounging for power supplies. My concern wasn't whether the power supply was enough or not (the Empeg lets you know pretty quick if it's not), my concern was whether a the 18v I saw on the tester was too much. I didn't want to blow an internal fuse or anything. For posterity: It was fine.