phase control doesn't really need to be messed with. The subsonic filter should be set about a 1/3 octave lower than tuning....What I heard as a rule of thumb...But usually I just use WinISD and set it so the sub doesn't bottom out and implode
Usually O or 180 is right. But if your bored get a friend and have them adjust the phase adjust (slowly) while your listening to the music. You will here a change. The point where it seems loudest and tight is the right point. Sorry, I cannot get more specific than that.