Beam does not support Bluetooth.

Do you want to add surround speakers?

Hey. Thanks for your answer. You are absolutely right, my bad. 
I meant casting the sound wirelessly with Airplay or WiFi. Do you think it is possible ?

This could get messy.

You need to support the HDMI-ARC audio channel input for BEAM. I didn’t see any simple devices that excited me. You’d also need a projector that supports HDMI-ARC. Later in the year some reasonable wireless HDMI-ARC extenders may become available.

If your projector offers an optical audio output, you could use a wireless TOLSINK extender and the SONOS TOSLINK to HDMI-ARC adapter.

Thank you very much for your answer, Buzz!

I wanted to avoid an additional device :/ 

Is it just me or it is a bit crazy that we can’t use a laptop as a simple mixer?

Some operating systems include a very crude mixing capability and I’m sure that there are some Apps. I’m not interested in any of this because laptop audio capability is usually poor and I expect there will be timing issues.

And it might be complicated by the fact that Sonos ‘works’ from the speaker level, and grabs the data from that perspective. The ‘controller’ is merely a remote control, showing what is happening on the speaker level.