Power question. I just built a home theater and put a dedicated 30amp circuit in my wiring closet, with only a 20 amp plug. Is the power cord on the 770 going to limit me to 15 amps anyway? or can I substitute a nema 20amp plug... and does it matter as it's limited to 1800 watts anyhow? confused. How many amps does the 770 pull under it's maximum load.