I have a problem with the above theory of disconnected load. There is no practical reason for the amplifier's (main) transformer to remain energized when the amp is turned off. The transformers in some preamps and CD players remain energized 24/7 once plugged in, with only the signal output muted. I have not seen it done with any amp, where the main transformer remains energized all the time while the load is disconnected. Amps that remain in standby when "off" usually employ a separate tiny transformer that is always on, to furnish power to the triggering/soft-start/protection circuitry. Otherwise the main transformer and power supply remain de-energized.