Please help: Hearing a high pitch "whistling" sound after stereo installation.
 

Car: 2000 BMW 323i Touring Wagon

Old Stereo: stock "hi-fi" (not the premium Harmon Kardon system) with 10 speakers

New system installed: Alpine 147BT, JL Audio 4-chan amp, Infinity BassLink sub. I kept the stock speakers for now.

The new head unit was installed first. The amp and sub were installed the next day by a different person. My system sounds great compared to the stock system, but.... when driving with the radio ON but turned down or low volume, I can hear a "whistling" (similar to some radio distortion) sound whenever I step on the accelerator. The pitch goes up the more I step on the accelerator, and goes down when I'm not. But this sound is NOT present when the car is idle or when the stereo is turned off. If I had the work done by one business it would be easy to go back to them, but since I had it done by 2 different people, neither feel responsible. What do you guys think the issue could be? Thanks.

No idea anyone? :dunno:

If the noise came after the amp was installed i would go to them. Does this happen when playing cd's or just the radio? Perhaps the amp isn't grounded good or maybe they ran the rca's on the same side as the power wire