Any change if you set gnome-mplayer to use software volume (its in the mplayer tab, or launch gnome-mplayer with the --softvol option) or you specify to not use flat volume (setting the gconf key /apps/gnome-mplayer/preferences/use_pulse_flat_volume to false)?
Any change if you set gnome-mplayer to use software volume (its in the mplayer tab, or launch gnome-mplayer with the --softvol option) or you specify to not use flat volume (setting the gconf key /apps/gnome- mplayer/ preferences/ use_pulse_ flat_volume to false)?