ok so i have and f 700 series, with an amp for subs and some Boston acoustics speakers.i used the good RCA and have well well ground, all cables have been routed correctly including i pod. So every time i switch track on the ipod source it makes a weird whistling noise and i will do it in the back ground but gets 30 times louder when i switch tacks, does not do it on cd or fm, and i tried unpluging the usb and using as an av and it doset make the whistling noise. What could it be? by the way i swaped the pioneer cable out this morning thinking it might be a faulty cables but it makes it exactl