Hi, I need a little audio advice and hope you guys can help. I have a Concert II + Bose factory fit stereo in my '09 A3, I also have the MFSW & BT Low prep w\ voice dialing. My iPhone connects to the interface automatically on ignition ..but it doesn't allow for BT Audio (A2DP). I'm considering upgrading the headunit to the RNS-E or a different make entirely, but would prefer a factory unit if the features are rich enough. So does the RNS-E allow BT music playback or is it limited to calling functions only, the same as my current system? Also, will my Aerial need upgrading if I go the RNS-E route? Thanks.