Install Sonos ceiling speakers in a concrete ceiling?!

If they are supposed to go under the ceiling, simply attach a ceiling outlet, a three-phase power rail to it, and click as many one as desired. Lighting can then optionally be connected!

So, Sonos has already responded. I have to say, they are really quick, the responses are always very fast and also written by competent employees.
It’s just like we have already found out: two wired front +2 wireless speakers plus a sub plus a „virtual center“ create a surround system that is capable of playing dolbydigital content in 5.1. Real 5.1 including center is only possible with the new arc if you add two rear speakers wirelessly or wired (together with an AMP). However, then you also!!! need the Sonos subwoofer, as the subwoofer connection on the AMP can no longer be used when it is used for rear speakers!
Regards and thanks for the information!