Yeah, but there isn't as much difference in sound as you'd think. Usually, with subs, reversing polarity is mainly when you invers the subs. I've had subs inversed before, and I couldn't hear any difference from shifting the phase.
it reverses polarity on the wires to the VC's. you would use it if you were having sub cancellation issues, of if you wired them wrong, and didn't want to take it back out of the box(i think).
thanks Joe, i have been wondering that for a LONG time, but i forget to ask when i'm on here. mine is set to reverse on my HU, and i switched it back and forth and noticed no real difference, so i left it on Reverse phase.