I installed a sub and amp on the factory 6-disc changer. I used an rca converter to provide signal to the amp via rca's, but my problem is this... I tapped into the left and right rear speakers for the signal. I raised the gain on the converter up from zero and the gain on the amp. The radio was set to 20. Amp was set to a low pass filter, NOT Full or HPF. It sounded good, except for when I turn the volume to 1-5, you hear very loud bass in the sub, basically nothing from the other speakers. The louder you turn the volume, the more you get from the other speakers, and relatively the same amount from the sub. Here's a twist though... When I connect an iPod, on some tracks you hear bass, on others, you get it from the factory speakers and little to none on the sub. Others sound fine. I would assume it is due to bad recordings. Maybe not? So my guestion is this... Do I have the gain on the converter set wrong? It's from scosche, is set to line out, and the four (+/-) wires for the rears are all that are connected. The Scosche converter is model: FAI3A, and the amp is a Jensen 2-channel bridgeable 300 watt amp. I know Jensen isn't the best and it's not a class-D for a sub, but it works. I had it lying around. Need any more info, let me know.