If you are streaming over a network connection, you're always going to be running into latency & buffering issues. Also, if you need the channels to be synced (ie. mixed down multi-channel piece), you need the system to set latencies among the speakers so each is playing roughly in sync with the other. Other than professional gear like massively-multichannel over Ethernet (Cobranet) or Coax/Fiber (MADI, etc), I'm not sure it would be that easy. AirPlay manages this automatically but I have no idea if it could handle that many devices as it's probably focused more on consumer situations, up to 10 devices probably.
On the other side of things, if you don't care about channel syncing as much, you could use an Icecast server and have the devices stream audio from the local server. This basically works like internet radio and you could probably have 16 stereo stream points or even 32 mono points. You'd need to stream from whatever is generating/playing the audio. There are a few options out there but almost all are focused on stereo, so mileage may vary.
In the opposite direction (streaming many to one), we did a streaming performance piece here last summer which forwarded live stereo mixdown from 4 performances across town simultaneously. Visitors to our studio space could then mix & "mash" (apply effects on, etc) the streams using various interfaces. I set up an Icecast server as the in between and was able to pull all 4 streams at the same time using concurrent VLC clients and forward them to Pd using JACK. It was clunky but worked pretty well after some testing.
Date: Sun, 17 Feb 2019 11:48:43 +0000From: Kerry Hagan <klhagan@gmail.com>To: Pd-List <pd-list@lists.iem.at>Subject: [PD] Pd & massively multi-channel wi-fi speakersMessage-ID: <23BF28C9-DEED-44F5-87D2-726AF5E874A2@gmail.com>Content-Type: text/plain; charset=utf-8Hello all,Has anyone used wi-fi speakers with Pd? More importantly - I would ideally like to send 30 independent audio channels to 30 battery-powered wi-fi speakers (in the same room)I’ve never used any wi-fi speakers for anything at all, and I’m finding it hard to see how they are connected without some proprietary software made by the usual suspects. I’ve scoured eBay, Amazon, Curry’s without being able to answer my own questions.And, best I can tell, the most flexible assignable speakers cost in the 100s or 1000s of USD/EURI’ve got a budget of a couple 100 euros at best.Any advice or pointers are welcome.Cheers,Kerry