The AUX jack is going to pick up *ANY* audio that's piped into it.

I'd be more concerned that the 2 devices would short out if they were played at the same time while connected.

Playing them just one at a time, though, I'd think there'd be no problem at all.

One interesting thing to note about the AUX jack.. if you unplug the cable from the jack, the head unit will go back to whatever was playng last on it.. radio or CD for example...

I beg to differ on that.. although upon reflection it occurs to me that the small amount of power that is there would most likely not be enough to fry anything. And there *is* power in any audio signal. albeit very small.