Even if your car’s factory radio is impossible to replace, you can still update the sound system with Focal audio accessories. Add an amp to a factory radio by getting Focal line output converters that allow you to connect hi-fi speaker input. Special plug-and-play adapter cables are available for the Focal Impulse-4.320 ultra-compact amplifier. Other factory stereo improvement supplies include multi-channel digital signal processors to clean up the sound. Get a 60-day satisfaction guarantee when you order from OnlineCarStereo.com.