My ignorance about avahi is probably showing but I don't see how it could be affecting this.
It was a hunch. Searching the forum for related problems brought up a post by a user with no sound who cured his problem by disabling avahi-daemon. Not all hardware is the same, so not all configurations and fixes are the same.
1) Well, okay. The offenders seem to be kmix and knotify. There's another mixer, installed by default, which is ncurses based, alsamixer. You can check out the settings by typing alsamixer
in a terminal, or you can install alsamixergui package from Synaptic. In any case, check the settings and see if anything looks amiss. (The alsamixergui has a lot
2) Be sure you're fully updated. After that, in Synaptic, click the Search button, change the search function to "Name", instead of "Description and name", then enter mix
. There will only be a few entries. See if you have extra sound mixers installed.
3) Sounds like you have a lot of sound playback programs installed. Have you checked the playback settings for each app to see whether you selected "oss" or "alsa" for playback?
4) Do you have JACK installed for a particular purpose, like musical instrument recording? If not, I don't see a purpose for having it installed, unless
some package pulled it in as a dependency.
5) I don't have kmix installed, so I can't check settings, etc. But checking dependencies for it in Synaptic, it does require some pulseaudio packages as dependencies. I didn't see the pulseaudio-daemon, though.
P.S. Two of the toughest issues to solve in Linux can be sound and wireless. You're in good company.