Aux Input noise on Rockford Fosgate

[714Titan]

Attention Titan owners with Rockford Fosgate system with Aux:
Need your help. I had recently taken in my truck to the dealer due to noise when AUX mode is selected. They claim this is normal which I have to completely disagree as this just started to occur a couple of weeks back. Here's how to duplicate this test...mind you that it must be duplicated excalty as described.

-Turn up the volume (10 shoudl be good)
-Set the radio to AUX mode...(all speakers should be silent at this point)
-Now, turn on your headlights
-If the dimmer switch is set to MAX, you will not hear the noise
-Now dim the lights and you should immedialtl begin to hear noise as if there is some type of interference.

If you have this problem, please confirm as Nissan states this is normal