Sonos removed the support for anything other than ARC and eARC. Even though you’re using the toslink/optical adapter that followed the Beam. I have the same product, pro-ject optical box E phono preamp. I have been without sound on both my TV and record player for over a month and Sonos does not care. Also been in contact with customer service twice and - nothing. 

I guess its best to just leave Sonos as a brand. I’m am literally disgusted. 

Hi @Felpeto 

In case you have not tried this functionality in a while, all Sonos products should now be able to play from an optical input.

If you are still having this problem, please ensure your Sonos system is up to date: Settings icon » Manage » System Updates » Check for Updates

I hope this helps.