Enter the "alsamixer" graphical interface can be set
Set the volume size (volume maximum):
amixer set Master 100%Gain adjustment can adjust the playback sound
amixer cset name = 'Master Playback Volume ' 99 // software gain
amixer cset name = 'DAC HPOUT Left Volume' 30 // codec headphone gain
amixer cset name = 'DAC HPOUT Right Volume' 30
amixer cset name = 'DAC LINEOUT Left Volume' 3 // codec speaker gain
amixer cset name = 'DAC LINEOUT Right Volume' 3