When you refer to sync ... do you mean sync between MC players. Or do you include DLNA renderers into mix too?
Now, thanks for asking. Unfortunately, I am a neophyte at this. That is why I have been asking for help on this for years. Maybe it IS possible.
Right now JRiver plays from my main Windows computer to the local PC speakers (a zone) and the receiver/stereo system its wired to in another room (another zone). I can play one, the other, or both. It works great, thanks to help I received on this forum several years ago!
What I want is to also have the following items connected via WiFi set as zones that play 1) synchronized in time and 2) volume leveled concurrently with my main system:
-Cell phones - Android and Apple
-TV to be purchased (audio and video), with soundbar
-Maybe Raspberry Pi's - They don't have internal clocks yet, not sure if that is a problem. I just set up an awesome Pi-Hole to reduce ads/malware on the home network! New announced beta 64-bit O/S is exciting...
-Other hardware/devices - I am willing to buy stuff within reason, though I try to stay away from the big Internet companies. Imagine a WiFi boombox playing whatever JRiver can play, cooperating with your whole network!
Currently, I am using an old cell phone, Gizmo, and Bluetooth speakers in the garage. It works as a separate entity, but it won't cooperate with my main system.
I want to be able to select which zones are playing at any given time. Whole home JRiver!
So I am not sure if I answered your question, but this is what I am referring to.