Why don't you just use a Beoplay S8 Connection hub?

I have toslink going into the beoplay connection hub then the powerlink to the speakers.

Having read this thread, I have a couple questions.  Sorry if I missed seeing the answers in this thread. (Reading on my phone). I have a Sonos connect that has toslink out. Instead of connecting to the line in if my Essence, could I connect via toslink to my 20s? If so, should the sound be better, same, or worse than through powerlink from my BV7? If better, can I have 20s connected to both powerlink for tv and Sonos for listening? Thanks!

My first post here... 

For those who say you can't have volume control using Mac/iMac optical out; in fact, ironically,  you can if you're running Windows under Bootcamp.

I'm planning to purchase a pair of BL20 in Paris this week and I plan to connect them directly to my iMac  ( OPT/SPDIF ). I rarely run OSX so it should be fine. 

Anyone disagree ?  

Current setup  iMac 27   --> DAC via Toslink ---> JH16 Pro IEM 

I've done some testings with my BS35 and its Google Cast features, with Android apps.

I observed different behaviors depending on the app used :

TuneIn : no software volume settings, but possible with the hardware buttons ; when pressed, the volume increase/decrease accordingly on the BS35.

Deezer : I started with the volume set to 10 on the BS35. On the app, the slider is on the left side of the scale. If I move it quickly and completely to the right side of the scale, and then release it, the sound is increased to 25 or 36 or other (it depends of the speed of my finger), and then the slider returns to the middle-left of the scale. If I do this again, from the last position, the sound is increased to 34 or 49 or other (still depending of the speed of my finger), and then the slider returns to a different position, middle or middle-right of the scale.

Looks like the scale receive feedback from the BS35 and is adaptive.

NB : only the slider of the app moves backward, the volume on the BS35 does not decrease during this.

DS Audio (Synology) : same as Deezer (some kind of adaptive scale), but the volume is increased by 10 each time, regardless of the speed.

I use my Chromecast Audio always at full scale with the BL5s, so I didn't notice anything.

I second that. I use a Yamaha WXC-50 with direct toslink connection to my Beolab 20's. The Yamaha has a 48bit digital volume control and it also includes a media player (DLNA, Spotify, Deezer, internet radio, etc.) and of course a user friendly app. I use it primarily connected with a Synology NAS which contains my large flac library. 

Whenever I want music to play, I just open the app on my iPhone and the Beolab 20 speakers power up automatically. And the Yamaha can just be hidden away somewhere if you don't like the look of it.

The only thing I miss on the Yamaha is some sort of color screen with album art and controls. Other than that I am really impressed.