The audio settings for USB are really just passed to jackd (the audio server) and if they don’t match then jackd won’t start hence no audio. The GUI logging in the webconf will tell you if this is happening. A very good starting point if it’s not working is by logging onto the Zynthian with SSH and giving the command: 'aplay -L' | The audio settings for USB are really just passed to jackd (the audio server) and if they don’t match then jackd won’t start hence no audio. The GUI logging in the webconf will tell you if this is happening. A very good starting point if it’s not working is by logging onto the Zynthian with SSH and giving the command: 'aplay -L' |