Sorry about the confusion the inbuilt Google Chromecast feature i mentioned wasn't discussing 5.1 surround sound where i was going off topic in a different direction (my bad).
Out of curiosity what is the make and model of your Soundbase and does it show on the soundbase display if you are receiving a 5.1 signal or stereo signal ?
It does offer bonus sports streams, but none have worked for me.
@staxvolt With Bonus Streams you need a full NowTV monthly Sports Pass (not Mobile Pass or Day Pass) and the Bonus Streams are only available during the live event.
I believe there is some Women's Golf on later this evening under Bonus Sports Streams.
I won't be much help, because i don't own a Sony Android TV.
On my Philips Android TV menu settings to get 5.1 surround sound to my AV Receiver via the optical out from the TV, i had to go into the Philips TV Advanced Sound Settings and from the three options of either Multichannel, Multichannel (bypass) or Stereo.
Multichannel without bypass (ARC) provides 5.1 dolby digital over the optical cable when watching Netflix, Amazon Prime App etc.