Kai, there was a commit related to this issue, can you check if it solves it?
pulseaudio (1:0.9.16~test5-0ubuntu2) karmic; urgency=low
[ Daniel T Chen ] * debian/patches/0051-leave-hp-enabled.patch: Leave headphones enabled in the default analog mixer profiles
In case that you still experience this issue after update, please let us now
Also you can check bug 387866, seems to be the same bug
Kai, there was a commit related to this issue, can you check if it solves it?
pulseaudio (1:0.9. 16~test5- 0ubuntu2) karmic; urgency=low
[ Daniel T Chen ] patches/ 0051-leave- hp-enabled. patch: Leave
* debian/
headphones enabled in the default analog mixer profiles
In case that you still experience this issue after update, please let us now
Also you can check bug 387866, seems to be the same bug