+1 I don't and have never used any audio output from my GPS. I do use my Sena to answer and make voice-dialed calls through my Android phone and use my iPod Touch to play/listen to music.
Of course, it doesn't help that my Zumo 660 has a known problem with its Bluetooth implementation (besides crappy audio fidelity) that makes it problematic to really use it paired with my phone and the Sena paired to it.
'09 R12GS, '05 GSX-R1000
Iron Butt # 4999, WERA/CCS EX # 666 (currently, expired), AMA Life Member
Racer, Drummer, Bassist, Software Engineer