When I first got my system installed in my car, my ipod wouldn't play through the subs, but it did play from the rest of the speakers. I asked the installer why, and he said I need a special ipod cable or something. Well yesterday I got a new charging cable on ebay for my ipod and I wanted to test it out. It was dead so I plugged it up in my car charger. The radio comes on, and music is coming from the speakers and subs, but I could hear a hum coming from the speakers that played with the engine. Whenever the engine would go up in revs, the hum would get louder. So I pulled out the charger just enough so that the light on the charger wasn't on, but it was still touching the metal inside of the 12v port. The humming stopped and it played through the speakers and subs like normal! Then I completely took it out of the 12v port, and the subs stopped playing, but the speakers didn't. So then I took the ipod, and placed the back of it, on the end of my e-brake handle, which is metal, and the subs came back on. So my subs are only working with my ipod when the ipod itself, or something connected to the ipod, is touching metal. Any thoughts as to why, and how I can fix it?