Hey guys I have a question regarding my speaker setup. I have a denon avr-3805 receiver, jbl e80s for the fronts and a klipsch sub 12 for my subwoofer. The speakers have dual binding posts for speaker hookup...however I have the positive and negaitve speaker wire in the top binding. My crossover is set on the receiver at 80hz. My problem is I am not getting any low end from my jbl speakers. Do I have to also connect the bottom binding posts on the speakers by bi-amping them?