I just received a Motorola HX550 and like it so far. One of its features is A2DP, which means I can listen to any audio through it, not just phone calls. However, I just discovered a little problem when I use it with my Alpine head unit, which has the dock connection for my iPhone. Whenever I turn on the HX550, it takes over the audio output and I hear the audio through the headset, not through the Alpine. The only way to change this is to go into the Music app and choose the Dock Connector. This would be okay, except what if I was driving and turned on the HX550 to answer a call? After I hang up, I would have to change the audio setting back to Dock Connector, while driving. Is this normal for headsets with A2DP, in that it takes over the audio even if the iPhone dock is being used, too?