Hi guys

I have on the Ultra the normal XM radio to which a HD mobile phone interfase is connected. Headset in both mine and the passengers helmet. Not a problem sofar but, now I want to add a Zumo660 satnav. I would have liked to get the Zumo's instructions over the sound system but, so HD tells me, this is not possible because of the phone interfase.
Has anyone had a similar situation and if so what was your way around it.
I hate the thought of earphones because that would block the sound of the radio.
I had thought a bluetooth 3rd peaker in the helmet but I assume the Zumo does not broadcast Bluetooth?
Any advise please?