Well I have sent a question to B&O tech support to ask about the synchronising aspect so we'll see what comes back.

It's worth saying that the whole reason for exploring this anyway is to exchange my large (v large) non B&O amp/passive speaker + Chromecast Audio system for the small BL3’s. But keeping the ability to simultaneously stream into the kitchen

So, even if it’s Essence Mk 2, this can’t do Multiroom on its own – if it sits in one room and connects to speakers by Powerlink, the speakers in another room will need their own wireless DAC box to provide connection to those speakers – so do you in fact need 2 x Essence Mk2?

Maybe a better (less expensive) solution is to have one Essence Mk1 in the room where I want a sub and turntable – here using the Essence’s built in Chromecast.

I then keep my existing Chromecast setup in the kitchen and use Google Home to group the Essence-Chromecast and the actual Chromecast Audio together – and there we have the Mutiroom ability and all the connections in the living room needed for sub and turntable.

This should work?