There may be a way to have the volume control the card. First check to see if alsamixer controls the volume. You can access alsamixer by starting a planyback of some sound and opening a terminal (ctl-alt-F2, user and password, alsamixer). If you can control the volume then somewhere the control link has been broken. If not the sound may be going through a "bit-perfect" mode and not adjustable. In that case you may need to change the settings in the media director.