My thought is that you might not find support for this setup and that classic receivers with zones are the current solution.
Over wired Ethernet it might work but Wireless and even then I'd worry about the old stadium effect (sound delays over air is physics which I'll note and stop here.)
Dear
I'm was wondering, before purchasing the Airport Extreme (http://www.macworld.com/article/2033878/review-apples-airport-extreme-is-a-safe- choice.html), if it was possible to connect my 3 Sony Airplay speakers (https://esupport.sony.com/US/p/model-home.pl?mdl=SANS310&LOC=3#/howtoTab) to the 3 LAN Ports of the Airport Extreme and airplay simultaneously as multi-room audio from my Iphone ?
Thanks for your cooperation.
Regards
Oliver
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