On customer request, we have integrated into miX-L a sound management which allows to play a default audio playback source (e.g.) radio or MP3 player). Volume and devices are controlled by our players.
The trick is that this audio signal can be automatically interrupted when the player instance will play a movie with sound. Thus, a constant sound is guaranteed - however TV or movies with sound will still be played with sound, without creating double sounds.

Even for video-IN, audio source devices can now be specified explicitly.