No, it is not possible to have a center speaker with Sonos.  All Sonos speakers for TV usage are either L/C/R built-in (Playbar, Playbase, Beam) or utilize a phantom center (Amp). 

Have you tried turning on the Playbar’s Speech Enhancement??

thanks for the quick response 

i tried to group the symfonisk with the Playbar and the play3s and got a weird echo from the symfonisk...

Grouped ‘rooms’ aren’t in sync with the home theatre setup for TV sound. (They are for other audio sources.)

This is because the HT setup can operate with smaller network buffers, and hence lower latency, to improve lip-sync.

yes i did. Speech is not the issue I just want to get richer sound from the center maybe the wallmount is the answer...