Comment # 12 on bug 922401 from Wolfgang Bauer

Ok, I can reproduce the problem with phonon-backend-vlc:
The overall volume stays at a sane value during the current session (unless the
right slider in KMix is set too high of course), but when I logout and login
again the notification volume seems to get reset to 100% and the next
notification raises the overall volume to 100% too.

Unfortunately the supposed upstream fix shows exactly the same behaviour.
The upstream patch lets you enable the volume control again though, and setting
a lower value than 100% there "fixes" the problem.

Everything seems to work as expected when using the default gstreamer backend
though. Even the test sound in the notification settings does _not_ raise the
volume to 100% in that case. (the test sound in the phonon settings still does
though, but that's another different problem)

So this seems to be a bug in phonon-backend-vlc. It seems to not remember (or
correctly set) the volume.

I'll report that upstream, but I want to check the situation in Plasma5 first.