Hi plante 14
Taking Stanley_4's advice (a step further) you might consider BT using Sonos. Here are the scenarios:
Advantage in either scenario
1. Users do not need the Sonos app nor access to your network
Scenario 1
1. Play 1's x 4_each named separately or 2 x 2 in stereo pairs
2. Sonos Connect (named as a room)
3. Bluetooth transmitter/receiver connected to Sonos Connect RCA or Optical out
4. Group the Play 1's to Sonos Connect
Scenario 2
1. Play 5 x 2 or 4_each named separately or 2 x 2 in stereo pairs
2. Bluetooth transmitter/receiver connected to Line-in of a single Play 5
3. Group Play 5's
See BT Transmitter/Receiver here: https://www.amazon.com/Aluratek-ABC02F-Transmitter-Headphones-Simultaneously/dp/B01N38BIMU/ref=sr_1_1?ie=UTF8&qid=1540158624&sr=8-1&keywords=aluratek
Using BT with Spotify: https://support.spotify.com/us/listen_everywhere/on_speaker/spotify-and-bluetooth/
Just a thought:8 Cheers!
Together Everyone Achieves More = T.E.A.M.