I have no sound on Xfce4. When I mute sound on Xfce (Or login to Xfce with the sound muted from the last shutdown), un-muting the sound doesn't actually un-mute all the sound outputs. It only un-mutes the master level, but not the speaker nor the headphone levels.
In the attached picture, when I mute\un-mute the sound, only the master level is responding.
My laptop is a Dell Inspiron SE 7520