I know this is an older thread, but the Nav5 can only Bluetooth music from the memory card in it to your headset. Having your phone paired to your headset and the phone paired to the Nav5 was only making things worse.
The Nav6 makes things much simpler as you can use the Nav6 to control music that is located on your phone. In this case, you pair the iPhone to the Nav6, then the Nav6 to your headset. Done.
The display on the Nav6 is waaaaay better too. I just upgraded from the 5 to the 6, so I have first hand experience.
Keith, let me know if you have any additional questions. Perhaps I could show you sometime at one of our rides. I will be doing the Oakland County ADV ride coming up in just over a week.