Hi
Not sure if this is any help, but have you tried reversing the wires in the sub woofer box. I am sure that I had an issue with a similar piece of hardware in the dim and distant past and if I remember correctly I got over the problem by swapping the cables around on the sub woofer box. I cannot remember exactly what I did, but I think that I had several issueswith the ZXR 750. If I recall I had sound that should have been coming from the front coming out of the rear speakers! I can remember that it was a lot of trial and error, but I got there in the end, experimentation could be the answer, ignore the correct plug settings and try different ones, it workedfor me, worth a try?