The BTR3K/BTR5 is only a Bluetooth receiver, so it could not connect to the Bluetooth headphone via Bluetooth.
The BTA30Pro could connect to the computer via USB connection and output to the Bluetooth headphone. 
But when connecting to mobile phone via USB, there may be compatibility issue because of the battery consumption.
And if you don't mind, you could try whether the BTA30Pro could work with your mobile phone and the Bluetooth headphone.