Car radio line in

I am building an mp3 player for my car using a pc board and using software to play the mp3's from a laptop HDD, then playing them through a sound card. The problem is I am on a budget and need an amp for it. I am planing on using my existing car radio, but it does not have a line in and I dont want to use one of those tape adapters as a lot of quality is lost.

What I want to try and do is find a way to wire it directly into the radio and have it amplified there, as the tape signal and tuner signals must both go into an amp somewhere in there. does anyone know if this is possible and how I would go about it?????

thanks liam

The reason I asked what kind of car do you have, is because some vehicles can use a special adapter that converts the cd changer connector at the back of a vehicle's stereo into RCA inputs for an auxilliary source.  That way, you get a direct audio connection and the sound quality can sometimes be better than with an fm modulator.

I don't think there's one available for your particular vehicle though, so your best bet would be to use an fm modulator.  Just make sure that you take a look at the back of your stock stereo to see what kind of antenna plug it uses.  The fm modulator (as well as virtually all aftermarket stereo equipment) uses a motorola-style plug, but many VWs use a different kind of connector.  If the antenna cable plugged into the back of your radio looks like this, then you'll need the two antenna adapters to properly install an fm modulator: Motorola M to OEM antenna F, as well as OEM radio M to Motorola antenna F.