A/V trouble shooting help

I am having engine whine though my system when I play the sound from my XBox through my Eclipse AVX2404. My installer had whining problems with my Concept headphones for my Vizualogic headrests so I am using the Vizualogic brand headpones. Now I just have whine when I play the audio from the XBox through my speakers. Since the Eclipse didn't have a line input for my XBox my installers had to use a Select SWI-X FM modulator. Does anyone have any suggestions on how to eliminate the whine or what I should check?

sorry my bad.. i don't have the brand name of the FM modulator used in my install..i was using my installation invoice and assumed that the (Pac SWI-X steering wheel radio control interface) was the FM mod.

first i would check the inputs to ensure proper connection and make sure they are nice and tight