In one whip (the one I drive most), usb plug into the ipod touch or classic (mostly touch nowadays...classic is like a storage unit when i want to hear everything, touch keeps more modern playlist). I either listen to my library or my offline library on Tidal.

In the other whip (the one my wife drives most) bluetooth everything (except the ipod classic)!!! Her car is newer than mine so when I hop in, it auto connects to whichever device I have it set on. I can do what I do in my car (without the wires) or I could use my phone and stream. What's awesome there is, I can also play youtube videos/music through the speakers. I have unlimited data so I don't sweat my plan or anything. Not like I use it that much either.

When I get a new car though...