Thanks for your answer.
I actually posted similar but more specific questions in this post
https://forums.plex.tv/t/plex-sonos-it-works-but-whats-the-best-set-up-local-does-it-exist-at-all-remote-or-indirect/740136
…but apparently no one was interested in responding 
Anyway, I still have a question if I may: why would Plex displays Sonos as being remote if the traffic is actually streamed on the LAN. This is quite confusing and did not give me confidence that it actually was to the point where I’m considering using Relay instead.
Thanks again for taking the time.
M.
