If you want to keep your oem head unit you could always get a sound processor.
Rockford has a model
3SIXTY.1
Interactive Signal Processor & OEM Interface (Patent Pending)
The 3Sixty.1 is the most advanced OEM integration processor on the market. It’s advanced artificial intelligence allows the use of aftermarket car audio equipment to be utilized with virtually any OEM source unit. In addition, it’s equalization process overcomes and corrects for any OEM equalization inadequacies. It’s auxiliary input enables you to add an iPod or other external audio devices.
15 wide Q filters (user adjustable)
6-channel high-level input
6-channel RCA level inputs (FR/FL/RR/RL/Center/Sub)
153 bands of equalization for OEM Integration
Auto equalization with auto sum capability
Auxiliary RCA inputs
Digital Signal Processor with OEM integration capabilities (patent pending)
Remote programmable master volume/aux volume control
Wireless Bluetooth®
OEM audio systems contain vehicle and speaker specific equalization. These equalization settings are not compatible with aftermarket equipment and will yield a less than desirable sound.
The 3Sixty utilizes powerful DSP processing to remove or "normalize" the factory OEM settings. This Auto Normalization process occurs automatically as part of the OEM set-up wizard. The net result is a flat frequency response with the dynamic range of even the finest aftermarket source units.
Additionally, 3Sixty allows installer access to all of the DSP audio functions(crossover, equalizer, level adjustments and time delay) via the PDA Bluetooth interface. This allows for an unparalleled level of sound adjustments to customize your aftermarket system to your audio tastes.
Process of OEM signal being fed into a 3Sixty
Connect OEM front, rear and subwoofer speaker leads into 3Sixty inputs.
Fine tune system by adjusting time alignment, x-over and output level controls.
Connect any auxiliary source (MP3, DVD, iPod®, Satellite Radio) to AUX inputs of 3Sixty.
2-Channel w/ OEM Speakers
Multi-Channel w/ Aftermarket Speakers
