Connection Question

What integrated amp are you using and what digital inputs does it support?

Your NAD C328 amp has 4 digital audio inputs (2 optical/2 coaxial). It does not have a USB input connection. If your Chromebook only supports USB output, you are going to need a digital to digital convertor was suggested above.

For example:

DOUK Audio Converter

I think the above will work but please confirm this.  Search on USB to optical converter for additional options.