Hi,
I've recently had a Nokia CARK-112 mobile phone kit fitted to an Audi A3. I
persuaded the guy to hook it up to the stereo which has connections for a
car kit and allows the sound to output through the car speakers (rather than
the small Nokia supplied speaker).

This works fine except that the sound level is too high - even at the lowest
level for the car kit/phone. I think putting some kind of potentiometer on
the cable from the car-kit to the stereo should allow me to reduce the
signal reaching the speakers. Can someone help me with this?
I believe a 10K potentiometer would do but have no idea how to connect this
(the potentiometer has 3 connectors on it).

Is there a better kind of de-amplifier solution?

many thanks for any advice.
Brian.