Even separate outlets are often on the same circuit in the same room (unless you've specifically set things up differently).

Clearly, the 770 can't provide full output to all channels @ 4ohms simultaneously and continuously. There just isn't enough juice to go around. I suspect that it probably can't do it at 8ohms either when you consider that the amp isn't anywhere near 100% efficient so you're losing probably 30-40% of the power as heat.

Anyone from Outlaw care to comment? Is my math faulty?

Cheers,