[tgittos]

I have a bunch of Sonos speakers and hooked them all up to a Mac running Airfoil (https://rogueamoeba.com/airfoil/mac/).

It isn't perfect and audio occasionally de-syncs or a speaker drops out. On a dedicated wireless channel playing a local source I imagine it would be pretty solid.

Not really an option if you don't have a Mac to run Airfoil, though if you do you can use the Satellite (https://rogueamoeba.com/airfoil/satellite/) program to sync Mac your other non-Apple devices to the host.