Car Audio Installation Accessories - Parts Express Installing a car stereo or speakers? Don't forget any of the cables, wires, relays, liners, baffles, adapters, antennas, and power accessories you'll need too. Car Audio Wiring Home > Car Audio Accessories > Wiring Accessories. Car Audio Wiring We have all the accessories needed to connect your amplifier power wire into your vehicle! We carry a variety of installation options including firewall wire grommets, wire couplers and fasteners to keep your install organized and maintenance free for years and years to come.