Byron, High School Physics can't handle this unless your school included audio amplifier technology in the curriculum. An HT receiver doesn't have separate amplifiers; there's one amplifier directing its output through several channels of output transistors. The output transistors act as valves to take the required amount of voltage from the one central power supply section to increase the incoming voltage at any instant, typically 25-30 times. The power supply section sets the limit on the maximum voltage that can be supplied to all the channels combined at any instant. Simply directing the same amount of maximum voltage available to a speaker through two sets of "valves"(one previously unconnected to a speaker)rather than one doesn't double the power available(as some imagine)and can't increase it by any amount. The output transistors in the several channels have no power of their own.
