Pac Audio: “Adjustable Line Output Converter” (SNI-35) This little device can make it very easy to connect an external speaker or subwoofer to the radio / cd player / etc system that your car already came with. You do not need to install a fancy new deck just to get line outputs that you can use with an amp and sub / speaker. Instead, the wires on this device can be twisted together with the wires leaving one of your car’s speakers. That way the audio signal gets passed from your factory-installed radio to the converter (just as it gets passed to that car speaker). The converter takes in the amplified signal that your radio & deck were sending to the passive speaker. It then converts it to an unamplified signal so that it can be run out into an external amp. The box features RCA output jacks for attaching to your amp. 10$ yo! Opened but never used! And I’m flexible - make me an offer. Also have a fuseable link and a JL sub, if you’d like them. And some cables.