PAC Premium Amplifier Add-On/replacement Radio Sound System Interface Kit GM - PAC AOEMGM1416 The factory amp (if equiped) & system will remain unchanged. Interface is transformer isolated, maintains phase and is linear from 20 to 20,000 HZ. This 4 channel interface will allow the output to be adjusted to the input requirements of the new amplifier, providing 2:1 gain and infinite attenuation. The input connectors plug into the factory stereo and vehicle harness. The 4 female RCA output jacks plug for connecting to the new amplifier.