输入“alsamixer” 可以图形界面设置
设置音量大小(音量最大):
amixer set Master 100%
调增益就可以调节放音的声音
amixer cset name='Master Playback Volume' 99 //软件增益
amixer cset name='DAC HPOUT Left Volume' 30 //codec 耳机增益
amixer cset name='DAC HPOUT Right Volume' 30
amixer cset name='DAC LINEOUT Left Volume' 3 //codec 喇叭增益
amixer cset name='DAC LINEOUT Right Volume' 3