Umm, This sound like a Sound Server problem. The KDE desktop runs the Artsd warapper sound deamon, and Gnome runs esd sound server.
I will advise ANYBODY to kill these services, as they are confusing the alsa and OSS sound modules ( as posted by Alan Cox on kernel devel mailing list ).
# killall artsd
# killall esd
Issue this in a term as root, while in your favorite desktop. Sound should work now. Let me know.
This has to be re issued at all boot, or some action has to be taken to remove these services in your init scripts dir ( /etc/rcS.d, /etc/rcX.d, where X is your runlevel number ).
If you want the front panel audio DJ buttons to work with Alsa, you need to install lineakd. Kde provides a GUI Front End called klineakd.
Anyhow here is the link :http://lineak.sourceforge.net/
Hope that helps.