Currently QAudioOutput will request audio data from the GUI Thread. This makes it impossible to write musical realtime Audio Applications with QtMultimedia.
All audio applications ( e.g. Ableton Live, Pro Tools etc. ) stream the audio data in the Audio Interface's thread.

If the audio data is coming from the GUI Thread, its not possible to use low latency buffer sizes ( e.g. 32 / 64 / 128 ) which are necessary for music applications as its basically impossible to make sure that the GUI thread never blocks the audio thread. When it does, it leads to nasty Audio dropouts.

Please consider improving QtMultimedia in this regard.

I could imagine that this could be implemented as another start() function, or a Mode flag etc.