Use an external BT transmitter such as the one in the link below:
Pair “Woojer” to the transmitter and connect the transmitter to your Xbox remote headphones output.
Next, connect your headphones to the Strap’s audio output jack.
1. As some controllers have weak audio amplification, in order to get higher audio and sensation levels you may choose to connect the Strap directly to the TV screen.
2. Remember to always set your audio source to HIGH volume.