Originally Posted by
Reid Malenfant
Strangely it reverses the phase, IE makes it 180 degrees out of phase compared to normal. This can be useful as you might have a pre amp or power amp that is inverting, if so then set it to 180 degrees or out of phase. If not then leave it on 0 (or normal).
The thing to do is investigate what either your pre amp, power amp or integrated does. At the end of the day though not too many people can detect out of phase signals. As long as both speakers are wired up correctly as in "in phase" that is, it's difficult to detect a phase reversal on both channels ;)