The Raspberry Pi Compute Module powering the StereoPi has the ability to operate as an USB device thanks to an USB-OTG hardware within the processor. This means that we can connect it to the PC and make it appear as an USB stick, a serial interface, or – as exposed in this article – as an external network interface. It is very powerful but it comes with a few limitations due to the architecture of the Raspberry ecosystem followed by the StereoPi. Let’s see how it works.

You can read full guide here:

https://stereopi.com/blog/stereopi-used-usb-device