You may be able to accomplish the same thing without turning the iPad BT off. My A2DP headset will connect to both my iPad and my iPhone at the same time, but will only stream audio (via A2DP) to the device it connected to first. To switch, I just put the headset in pairing mode (which disconnects both devices) then re-connect with the device that I want to stream to (from settings menu on that device). After that the other device will automatically re-connect, but I can stream from the device that connected first.