Don, a further comment would be that you used "amps" and "channels" as if the two were synonymous. A receiver has only one amplifier with several channels to distribute its output. The output transistors in each channel simply act as valves to measure out the required voltage from the power supply section. They have no power of their own to create a doubling or any other increase.
John- I may be living in the past (I have plenty of it!). In my experience the output stage does have gain, that is, it amplifies the signal coming into it. A (relatively) small voltage at the input of the final (output) stage causes a larger voltage at the output of that stage. Also, the impedance that the final stage is driving is usually much lower than what the prior stage drives (the input impedance of the final stage), so the power gain is considerable. Your description would mean that the final stage has unity power gain, is that the way modern amps are built? I'm familiar with 1-output per channel stereo amps, but not 5 or 7 output per channel amps, maybe this splitting of the signal is where the unity gain comes in.
