There are two basic methods:Originally Posted by skaska
- Run the audio out into an aux input on your car stereo, which then feeds audio to the speakers. The head unit could also feed to amplifiers first.
- Ditch any 'traditional' car stereo and use the audio out on the PC into an amplifier, then to the speakers. This is the route I'm taking, which will give me A front L/R channel, a Rear L/R, and a Sub. This method is also more prone to electrical interference causing 'noise' that lowers sound quality.
Do a search on the site and see what's worked for other people on their projects.