Spotify seems to have new stuff for sending audio to remote speakers. They call i spotify connect. This is my reverse engineering effort.
There seems to be an initial query to mdns which asks for _spotify-connect._tcp.local.
_spotify-connect._tcp.local: type PTR, class IN, "QU" question
I tried creating a service file for avahi which answers and spotify seems to crash some times.
dig -t ptr _spotify-connect._tcp.local @18.104.22.168 -p 5353
On a working system would be great.
More to come...