The PAC AP4-GM71 AmpPRO 4 is a premium amplifier integration interface designed specifically for select 2019 and newer General Motors vehicles equipped with Bose® Ethernet audio systems. Engineered to simplify aftermarket amplifier installations, the AP4-GM71 allows you to dramatically upgrade sound quality while retaining the factory radio, OEM controls, warning chimes, Bluetooth®, navigation prompts, and telematics functionality. Built with advanced AmpPRO technology, the AP4-GM71 provides six channels of high-quality 5-volt RMS preamp outputs with retained fade, balance, bass, midrange, and treble controls directly from the factory radio. The interface also includes a TOSLINK optical digital output for advanced DSP and premium digital audio system integration. Key Features: Designed for select 2019+ GM vehicles with Bose® Ethernet audio Retains factory radio and OEM vehicle functionality 6-channel 5V RMS preamp outputs Retains fade, balance, bass, mid, and treble controls Includes TOSLINK optical digital audio output Retains warning chimes and telematics audio Retains Bluetooth® and navigation prompts Plug-and-play installation design Remote amplifier turn-on output included Adjustable subwoofer level control included Compatible with aftermarket amplifiers and DSP systems Audio Integration Features: Variable 5V RMS RCA outputs Front, rear, and subwoofer outputs Variable 2-channel optical digital output Adjustable minimum volume and chime volume OEM audio retention with upgraded amplifier capability Data-controlled remote amplifier output Vehicle Compatibility: Select 2019+ Chevrolet vehicles Select 2019+ GMC vehicles Select 2019+ Cadillac vehicles Select 2019+ Buick vehicles