That's a trick question.
I noticed that there was no bass when I played a DVD. I thought it was broken, but then I did have bass out of the stereo. (that's what the line checks).
Apparently they were connecting the AMP pre-out/power to the power antenna wire from the chassis harness and not the amp wire. This means when the DVD is playing there is no bass, no power to the power antenna wire. If your stereo has bass but not DVD...then that is the reason.
PLEASE do not send questions via Private Message, my inbox fills up too quickly. Post questions in the forum as a new thread so that other users can benefit from the answers. Use Private Messages for sensitive information only (VIN, Contact info or things you do not want the public to see).