ALSA asound.conf

pcm.AndroidPlayback_Speaker_normal {
    type hooks
    slave.pcm {
        type hw
        card 0
        device 0
    }
    hooks.0 {
        type ctl_elems
        hook_args [
            #省略部分
            # I2S IN -> DAC -> spk mixer -> SPKOUT
            {
                name 'DAC fun Mux'
                value 'Stereo DAC'
            }
            {
                name 'SPK Mixer DAC Mixer Playback Switch'
                value on
            }
            {
                name 'SPK Vol Input Mux'
                value 'SPK Mixer'
            }
            {
                name 'PCM Playback Volume'
                value.0 50
                value.1 50
            }
            {
                name 'SPKOUT Playback Volume'
                value.0 31
                value.1 31
            }
            {
                name 'SPKOUT Playback Switch'
                value.0 on
                value.1 on
            }
            #省略部分
        ]
    }
}