I know on my dads 05 f-250, he has a JL 10w-7 you can hear some humming with the sub when there is 0 vol. also, as with the center channel. But not as loud as you are explaining. We are "unsure" what is causing it, but its VERY MINUMUL, easy to live with..
It might be your H/U? idk (if u havent already) check the speaker/tweeter connections..