Aux Input - Tea2025 Amp Noise

Hello! I'm not sure if this the correct forum to post this question in, if not please point me in the right direction.

Here's my situation. I was bored at work and thought that it would be cool to tap into my CD Changer line into the headunit so I could listen to my Iphone. I came up with a circuit board that would recognize when the Iphone was plugged in so the relay would switch over and I could still listen to CD's when the Iphone wasn't plugged in. Everything worked well except I had to turn the headunit up really loud so I could actually hear the Iphone, which it turn caused the sound quality to be poor.

So the next revision of the board I created, I used a TEA2025 amp to increase the volume. I also connected one POT for each line so I could control how much volume I was adding.

The problem that I am having now is that when I plug the Iphone in and the car isn't running it sounds great. But when the car is running, I'm getting interference/noise through the speakers, almost like static from the alternator.

I have changed the location of ground a few times thinking it was a "ground loop" but nothing. I am starting to get stumped. Sorry this is a long post, but wanted to be a precise as possible. Please help! Thanks