12.How to use USB audio functio to connect the M21 to an external decoder?

The M21 supports external USB audio. The setting steps are as follows.

1.Enable "USB output" in the FIIO Music app on the M21.

2.Use an OTG cable to connect the M21 to the external decoder.

3.Open the FIIO Music app or other music applications to use the M21 as a USB digital output device.

It supports most decoding devices on the market. For those unsupported, you can turn off the USB output in the FIIO Music app, or unplug and re-plug the USB device after quitting the FIIO Music app. If it does not work, please contact us by sending an email to support@fiio.com for further help.