Another vote for the HiFiBerry. I’ve used their Digi+ board (which includes optical-out) with a Pi3B running Volumio for a couple years and it’s been fantastic.
If a company could get the kit price under $40-50, I would definitely use them for more one-off projects. Aside, I really wish that Docker for (Windows|Mac) ran as a service without requiring login so I could run background linux software with a little less friction. The linux on windows stuff is coming along, but similarly lacking initd/systemd startup. And while I know that a desktop os isn't a server, I've got a plenty powerful desktop that I have always on, and would just assume not have another computer running.