It is more than likely a ground loop. You need to add a ground from the head unit and the black wire to the body. The humming is almost always ground related.

 

It was the ground wire off of that Scosche Line Converter. I had connected that ground to my other grounds, and as soon as I cut it off and attached the other grounds without, voila! No more buzzing! I taped that ground wire off since apparently it wasn't helping anyone.

Perfect silence... Ahh. This is really great. All my steering controls are working, and I can use the mode button to talk to Siri and send texts or talk through the mic behind my steering wheel, and Bluetooth my phone or USB it in for charging. The head unit with the din sleeve still attached pushed in perfectly snug too with no need for screwing, and it's not going anywhere.

So this is what everyone else feels like driving new cars with these features. Pretty handy. But I'll take my Disco II style any day over the newer ones.

Thanks a million fellow Rovers!