While the quality of audio probably degrades down the line in that order, I was wondering by how much. I've never had any experience with audio over BT other than the BT headset for phone calls. I'm very interested in buying 2 sets of Cerulean XR+TR set for the iPhone. I read that it has been confirmed to work with iPhone for Audio. This option would be great for me. It would mean less wires in the car and at home. My concern is the sound quality and I haven't seen Cerulean XR+TR anywhere other than online. What's the sound quality like on this thing? or other similar BT audio transmitters? compared to FM and line out?