This is exciting. About 5 years ago I tried to set up a home-made Sonos clone by using two Raspberry Pis to stream synchronised audio across my network. I did get it to work, but it was a huge hassle finding the particular combination of PulseAudio configuration flags to use, and I had to set up a dedicated wireless network for the bandwidth because it fell over if I used compression. I figured the best approach would be to write a PulseAudio module in C but I never had the time or skill to do it.

I'll definitely be giving this a go!