The chances of you actually drawing all the power the 7900 can pull at the same time is minimal. Although it is rated at 450 watts to all 7 channels, you would have to have speakers attached to every channel which could handle 450 watts. An unlikely scenario since we almost all have smaller centers and surrounds than mains. All told it could pull a continuous 3200 watss or so in those circumstances. Providing it plenty of power is good for transient response but unlikely to overload two 15 amp circuits which should supply 3600 watts.