If you’re running KDE and Pulseaudio and have the problem that you can’t configure your audio sources in KDE’s multimedia settings, there might just be a component missing:
apt-get install vlc-plugin-pulse
I’m not sure if this is usually part of some KDE desktop metapackage, but for me this package had been missing and one of the symptoms was that only “alsa” and “oss” were shown as audio sources, with no sound playing at all. Those icons also had little VLC traffic cones on their heads.