Today's modern vehicle audio systems are becoming increasingly more sophisticated and complex. PAC engineered AmpPRO to dramatically simplify the installation of upgraded amplifiers in data-bus-controlled amplified sound systems. AmpPRO allows you to keep the original radio's fit, finish, and features while giving you the freedom to improve the audio performance in record time! BENEFITS: Factory sound system upgrade Time-saving design Prevents the need for summing and audio correction devices Reliable PAC quality FEATURES: Upgrade solution for factory, fixed level, data-bus controlled sound systems The time-saving design prevents the need for summing and audio correction devices. Variable volume, fade, balance, bass, mid, and treble audio settings Retains OnStar, Bluetooth, navigation, safety systems, and all warning chimes Front, rear, sub, and center channel preamp outputs (5 volt RMS) Provides full range, flat audio output for a solid audio foundation Customized OE bass, mid, and treble center frequency selection Plug-n-play installation Remote sub level controller INCLUDED Optional TOSLINK optical output INCLUDED INCLUDES: AmpPRO module Harness Bass knob Knob harness MANUAL: Also available for fast, easy install: APH-GM02 harness (sold separately) UPC: 609098826105 HOW IT WORKS: