Comment # 8 on bug 922401 from Wolfgang Bauer

(In reply to Christian Bachmaier from comment #7)
> > IIRC, playing a system sound in the KDE control panel will always play it at
> > 100%.
> > So don't use that to verify the volume.
> 
> If you are asking me, then this is also a bug: playing a sound manually in
> control center resets both loudness sliders to 66% instead of leaving them
> as they are.

Yes. But that's a different bug, and also exists without PulseAudio.
In the latter case it doesn't cause the same problems of course (because it
will not change the overall system volume).

> 
> > But actual notifications should be played at the correct (lower) volume.
> 
> Unfortunateley, no. As I wrote, the automatic login notification (or some
> other) resets both sliders to 66%.

Well, the question is whether this is really caused by the login notification,
or it is some other problem like incorrect restoring of the sound volume on
boot e.g.
Is this also happening while logged in whenever a notifcation plays? Is this
also happening if you disable the login notification?
And as I already asked: have you tried with a fresh user account too? (might be
a problem with the saved volumes of your user account)

I don't use PulseAudio myself (because of other reasons), but I also haven't
experienced such a problem when I tried it out (with 13.1 and 13.2)
But then, I never had the login notification activated (it is disabled by
default).
I think I will install/enable PulseAudio again and play with this over the
weekend...