When I think of phase issues, I think speaker wiring gone bad on one of the speakers.
This is not hard to notice as the soundstage has no focus.

Playing with the phase setting in direct mode on my G68 I can hear an initial .5 second change in the soundstage, then back to the same. I hear no difference between the +/- setting.

So.. my question .. what does "phase" do?

/SA