Choppy Bluetooth audio: How to persist Bluetooth bitpool settings on Mavericks?
To force the system to use USB Bluetooth by default, try the following command:

sudo nvram bluetoothHostControllerSwitchBehavior=always


This will modify your boot kernel arguments.

To do opposite, use never. The change would be applied after the reboot. To return to the default, run:

sudo nvram -d bluetoothHostControllerSwitchBehavior