It's simple, click X and it's gone, but it's driving me crazy. Everytime I login, Kmix reappears, centered on the desktop, which I have to close out. I figured it was a KDE session issue, I have tried closing Kmix, logging out, adjusting settings in KDE configuration to not save the session, etc. I run beryl, so I have turned it off, and I still get the same result. If I could find where KDE stores the session information, I could try deleting that, but I don't know what file that would be or where it is kept at. Anyone have any ideas?

in kde control center -> kde components -> session management in the middle you can choose if you wanna restore the previous session, a manually saved session or an empty session. Choose 'restore manually saved session'.
In the kde menu you should find then at the bottom (where the logout options are) an option to save the session. Setup your desktop like you wanna have it at startup and then choose 'save the session'.

Well, that was worth a try, but the curse of the Kmix window continues. Do you know where the session info is stored?

well, I'd start in /home/whatever/.kde/share/config. Look at kmixrc first. Set AllowDocking=true and visible=false. Maybe this can bring victory over the kmix curse.

edit: also take a look at .../.kde/share/config/session. It may contain a kmix-file, which stores evil session information.

Thanks for all the suggestions. Unfortunately none of them was successful. But the curse has been broken. I used synaptic to uninstall kmix completely, then shutdown to save the session, reboot, reinstall, and everything works as expected.

Are you running MEPIS?

Drove me nuts too.

Guess you can run alsamixer instead.