Real multiroom/multi zone audio system with multi source-multi output

I’m just few weeks before cabling my new house with all possible smart home solutions (lights, doors, roller shutters, heating, cooling etc). Since few weeks I’m looking for a solution for multi room – multi source audio system. The problem is it should be scalable, the best would be to send audio over LAN network (all house will be wired with gigabit LAN). So before putting much to much cables for sources and speakers I was trying to find solution to avoid unnecessary cabling all the house with even more cables.

I would like to be able, to use my audio system either independent or partially/fully synchronized. I would like to keep all the possible audio zones independent, at least it would be:
– living room
– kitchen
– bathroom 1
– bathroom 2
– terrace
maybe also later
– fitness room
– office

Because you never know the future ideas, this is why I would like to be able to keep the system scalable. I like the feeling when every single door is open, you move over the house and hear everywhere the same music. At the moment in my old flat it is just possible if I turn the same analog radio station in each room. But it would be the best to be able select any source for any room/zone, like:
– TV
– Spotify/webradio
– own music collection
– any AUX device – like lokal Radio reciver, CD player, turntable, computer etc
– bluetooth device – smartphone, laptop

I was trying to put some schematic together, how it could look like:

I was trying to find any working solution, but there is a lot of informations about low latency audio streaming, but there is no information about how to get it done. I belive there must be any working solution that may apply to my requirements. After viewing few videos of Max2Play I though it would maybe work like I wish to.

If this would be possible with your system, which and how many licences would I need to buy?

What about the latency in your system? Would it be possible to watch TV/Movie and play the sound through Max2Play without feeling the delay in Audio?

Thank you in advance to help me!