As you can see, the thing has a switch: "TX/RX"= transmit or (!) receive. It does not run synchronously, it is too simple for that. But it's enough. What bothers me about the external Bluetooth receivers, which has nothing to do with Hama, is that they send very quiet signals to the system.
You have to turn the system up very loud, and don't forget to turn it down again afterwards. Otherwise the neighbours will start a riot ;-) All the best! Bliibet diahi