Capacitors?
I know what a capacitor is, but I’m a novice at car stereos in general. All I have is the head unit (a Kenwood) and the speakers. All wiring is factory. I’m not aware of an in-line capacitor between them. And the head unit (from what I can remember when I put it in) is pretty basic on the rear. Pre-channel outputs, antenna plug, and wires for power/speakers.