I have a Blaupunkt stereo in my car. I bought the Aux cable for the ipod (music plays through the cable and and charges the ipod). It works great but there is a hiss noise. I hear it even when the car is off and the noise does not change as I drive the car. It is a steady small hiss.

When I use the front 3.5 jack everything sounds great until I plug the ipod in to charge it.

Is there a way I can eliminate the hiss? I have no idea what causes it but it seems to appear when I am charging and playing the ipod at the same time. If I use a noise reducer device through the 3.5 jack it takes the hiss out. But I want to use the Ipod aux jack in the rear of the stereo and find a way to eliminate the hiss.