Hello

If I do this, the behavior is the same as described in my previous post:
- in Band in a Box: midi sounds but not RealTracks sounds
- mute sounds as soon as I remove the track "GarageBand Apple DLSMusicDevice" or as soon as I close Garageband

If I create a GarageBand track with AUMIDISynth or AUSampler, it's the same. The only difference compared to AppleDLSMusicDevice is that all midi notes in Band In A Box are played by a single sound. Whereas if I select AppleDLsMusicDevice, I have all the sounds of the arrangement (bass / piano / drums / ...)