I’ve seen a few DIY projects online about creating a SONOS alternative but I’ve not got the time to hand to put in the hours these people seem to have done.
My ideal set up would be my living room, kitchen and study to have synced audio using the speakers I’ve already got. I don’t suppose anyone know’s of a device which is capable of doing this.
I’ve done this the derpy DIY way in the past, get a radio transmitter, plug into source with a 3.5mm jack and and just use receivers wherever plugged into anything you like. I paid $5 on ebay for sender and can pick up on phone, car, or dedicated radios within about 15-20m, sounds as good as a normal clear radio station, so probably not audiophile suitable, but as good as normal multi-room fill with untreated spaces will be anyway. If worried about regs, you can be Bluetooth ones for like $15, not sure if there is a limit of pairing multiple at once though, so you many need several senders. If you can, you WILL get best results running a cable I suspect.
Also from the other thread… this is economical if limited rooms.
You can set up groups if you have multiple chromecast audio’s