I'm using USB sound card (GeneralPlus), audio output is working fine, I can hear sound in USB audio card.
However I can't make the microphone input to works, the microphone device is detected by 'alsamixer' and 'lsusb' command, but no sound.
Also LibreELEC seem removing some alsa-utils command, like 'arecord' and 'alsaloop', is there a way to make microphone works ?