Lately I've developed a really annoying problem. My setup is a 1999 JVC KDSH99 H/U. & a JBL BP1200.1 amp. As soon as I turn the volume up my subs go crazy, they'll move and I don't get any sound. If I put it on CD/AMFM I get sound. When I do I still get the crazy sub movement. My H/U is...