These adaptors allow you to install an aftermarket amplifier to your factory head unit. These devices take the speaker level outputs from the head unit and reduce the signal to a level of which an aftermarket amplifier can use without overloading its inputs. APHL2A This will convert your existing cars factory head-units high level (speaker output) into a line level (RCA) output allowing you to add on an after-market amplifier speakers or Subwoofer.
