I may be missing something but this appears to me to be a WebRTC application. It is very easy to build something like this using any modern browser's WebRTC APIs, just disable audio processing in the media constraints and munge the opus SDP to stereo, maybe play with the network buffer setting if you want to lower latency but the audio hardware and physical distance is going matter more there.

The developer states that no other software was suitable, and also that it's the first of its kind. Both of those statements are not accurate: there is nothing innovative in sublive that isn't in any of the apps listed below. Props to the developer though for scratching an itch.

https://en.wikipedia.org/wiki/Comparison_of_Remote_Music_Per...