Oh, my goodness. I have four speaker leads and different amplifiers on the treble and bass. Everything is bound to be out of phase. That's why my system sounds so bad. Oh and as for the subwoofer, even more out of phase.
I have to wonder how they manage in the recording studio. Do all the microphone leads and all the direct record systems have to have identical paths between the music source and the mixing desk. Er, it does seem to be unlikely.
I haven't seen any 50 piece orchestras sat identical distances from every listener. Nor have I ever seen a piano with strings arranged to be the same distance from anywhere.
Or, in other words, ballcocks.