Phonon: "Pause->change media source->play" let play AudioOutput with full volume

The following procedure changes the volume of an AudioOutput object to full volume immediately:

1. Set a volume (for example calling setVolume(0.5) of the Phonon::AudioOutput)
2. Play a media file (MP3 for example)
3. Pause (calling pause() of the Phonon::MediaObject)
4. Change media (calling setCurrentSource(...) of the Phonon::MediaObject)
5. Play again (calling play() of the Phonon::MediaObject) -> Full volume now!

It seems the correct volume which was set before by using setVolume(...) on AudioOutput is still stored but somehow gets overriden by the procedure above until setting it again using setVolume.