Ok, I think I may have been confusing myself. As long as I pick a sufficient relay with a high enough coil resistance (e.g. http://www.radioshack.com/product/in...ductId=2062482) it shouldn't matter how much current is required to drive my amp's remote lines (as long as the switched +12v wire from the battery is of a suitable gauge), correct?
The only current following back across aux_sw should be the current required to energize the relay's coil. Do I have this right?