I run all my 7.1 system off the 770 and the sub, TV, etc from a 15A circuit and the current meter on my panamax never goes above 10A, even when listening in mono to drive all channels the same.

When I did concerts in college and the first time we rented a generator to run the set up, we spec'd the generator based on the max load, but when we cranked pink noise thru all the channels/sub for the 40KW sound system we never got above 35% of the max we spec'd with our current clamp. The lights on the other hand, they drew near their rated power. We subsequently rented smaller generators using 50% max for the sound later and it always worked. These were all Crown Macrotech amps, which were awesome amps, could drive down to 1ohm loads easily.