I figured out that it is related to pulseaudio. When i purge pulseudio and rely on pure alsa, the faulty behaviour is gone.
- Bug#842842: [phonon] Audio device profile gets changed w... Georg Gast
- Bug#842842: [phonon] Audio device profile gets chan... Georg Gast
- Bug#842842: [phonon] Audio device profile gets ... Maximiliano Curia