Re: How many watts is my sub getting
No, really. Mr. McCulloch did not misspeak. Amplifiers (as Silas points out) are voltage amplifiers. They happen to have a current reservoir behind them.
What your missing (in regards to "power amplification") is that the impedance of a speaker is not constant WRT frequency. As the frequency of a signal changes, so does the resistance of the loudspeaker. This frequency-resistance relationship is called impedance.
A speaker is not so much a machine as it is a "motor." A motor is a device that converts one form of energy into another. It does produce power and it does not "absorb" or store it either. In converts some energy to motion, and most energy to heat. The rate at which this happens is power.
The same is true of an amplifier. It could be considered a machine, as it changes the direction (phase) of the electrical energy that supplies it. Similarly, it produces power. It changes the phase and frequency of some energy and like the speaker (machine part), converts a good bit to heat (power).
Overall, you could say that a "power amplifier" is not really a power amplifier at all. It may (or may not) increase the power of a signal whose voltage it is amplifying... dependent upon the impedance of the load.
