Ground loop problems in car audio are notorious for interfering with the enjoyment of the system. Whine and speaker oscillations are significant issues, caused by excessive direct current on the alternating current audio signal. One trick used by experienced professionals and DIY installers is the practice of grounding the RCA shield. This technique, while not 100 per cent effective, is another tool in the arsenal of the mobile installer, and is at the root of balanced cable theory.
Remove one of the RCA leads from the amplifier's input jacks.
Cut a length of primary wire sufficient to reach from the RCA jack to an open screw on the chassis of the amplifier. Do not use a screw used to connect power, ground, or remote terminals to the amp.
Remove the screw using the appropriate screwdriver. Set it aside in a safe place.
Strip the ends of the primary wire. Strip one end so that the bare wire is the same length as the inner ground collar of the RCA. Crimp the 16 gauge insulated connector on the other end of the wire.
Place the tip of the bare primary wire inside the RCA's collar. Slide the RCA back over the jack. It may be necessary to fan the bare wires to facilitate the connector's fitting on the jack.
Place the chassis screw through the ring terminal. Secure the chassis screw with the correct screwdriver.
Do not make any system connections with the system or vehicle turned on to prevent shorts.