Make sure that the AVENTHO 300 is switched on and connected to the playback device via Bluetooth. Take care that the "Audio" or "LE Audio" function is activated in the Bluetooth settings of the AVENTHO 300 in the playback device. Make sure that the volume is set to a comfortable level and start playing the music.
Tip: If there are other Bluetooth devices nearby, temporarily deactivate Bluetooth on these devices so that the AVENTHO 300 is only connected to the desired playback device.