A line out converter, or L.O.C., is a device that turns the speaker-level audio signal in a car audio system into a line-level signal that one can connect to an amplifier. This is necessary when one is adding an amplifier to a factory head unit, since factory head units do not have RCA outputs to get signals from. Typically, L.O.C.s come in two and four channel versions for a variety of installation options, and may be easily removed to...