Is there some kind of parameter or specification that indicates power cable bandwidth?I've never seen one... it would be a good spec to include.
Looking at @dep14 's calculator, it looks like for a typical home-use power cord (16/3 cable at 6' in length) you're only losing .6% of your voltage on a typical 120v 15a home circuit,
In practice you see more- the problem area with many inexpensive cables in the connection at either end. That is where you are most likely to discover that the cable is heating up and this calculator does not take that into account. It also does not calculate the impedance of the cable at higher frequencies, so I can't regard it as 100% accurate, although for general home electrical stuff its fine.
The problem here is that, like it or not, you can hear differences between power cables. My thinking is that if you can hear differences, there should be something measurable as well. I find it easier to measure the effects on the equipment with which the cable is used rather than to measure the cable.
In a class D amp, the idle current is quite low. But to actually make the power to drive real speakers, the amp has to draw power from the wall and at full power can draw quite a lot depending on the amp. If you were to put an ammeter in series with the amp's AC power, you would see the meter dance around as you ran the volume up while playing music. The thing is, switching amps need the power supply to be quiet and the current it needs has to be readily available. Most of the expense of any class D amp is its power supply.
