noob: Adding LED to outer casing of headphone shell

I don't recall the actual wattage involved in headphones/earphones, but it isn't much and the voltages involved are probably tiny by comparison with what an LED would need. In addition, the current required by the LED would very significantly affect the sound, if the voltages were high enough and there was enough power in the audio for continuing to consider the idea. And then finally, I can't imagine you'd get enough energy in any given flicker that you'd actually see it. You could try it, of course. But I think you'd be disappointed both in the sound as well as in the LED's appearance.

It would seem to me that you could add a power supply to all this. But then they wouldn't be the headphones you know and love. They'd get heavier for the weight of the battery and they'd look cumbersome with the circuit and battery present. It might be possible to recable them and add another pair of wires for a real power and ground supply you could use with a circuit at the headphones. Or add a wire pair to drive an LED, separately, and keep the supply AND circuit back at the box with the jack, but then you couldn't use standard jacks, anymore.

Jon