I saw something new when I looked at this again:
Do speakers draw watts from an amp or get fed watts ?
I see why it's tempting to conceive of speakers as drawing power from an amplifier, but here's a parallel situation: if a pipe connects a lake of one elevation to a lake of a lower elevation, does the lower lake draw water, or does the upper lake feed water? It's definitely the latter.
The difference in elevation provides a force to move the water to the lower lake: the force of gravity. With amplifiers and speakers, the voltage at the amplifier output provides the force to move energy into the speakers.
The diameter of the pipe and the difference in elevation of the lake determine how much water will flow. The impedance of the speaker and the voltage of the amp determine how much energy will flow into the speaker.
