Just wondered if anyone has answers to this. I have the panasonic with psb alphas front, paradigm3se minis rear, sound dynamics passive sub and center. The sub is connected to an older pioneer amp that is connected to the pre-out of the receiver. The problem is when I set the bass and treble to flat on the reciever the sub sounds fine but as soon as I change it the sub drops off. This only happens in the stereo mode and it doesn't matter if the the speakers are set to large/small Any suggestions or reasons why? I am hoping to purchase powered sub soon.