I bet you could pair a couple devices, and have both of them active...
AFAIK, you can use one of each type of device at a time... like one headset at a time... etc etc...
What I'd DIG is a head unit with Bluetooth that can connect to a PDA and read files from it, so that you can put music files on your PDA, and listen to them through the head unit... or a head unit that has a headphone profile, so it can get stereo audio from a PDA.
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2001 Boxster - Grey on Grey
1969 911T Targa - 'Stinky'
http://www.zoto.com/frayadjacent/img...f27a-4a399.jpg <---- my car. ^ crap I post.
"The existence of the flamethrower is evidence that someone, somewhere once said 'I want to set those people over there on fire, but I don't want to have to walk over there to do it.'"