The synchronization of multiple zones is definitely non-trivial. Many years ago I had a few Apple Airport Expresses which had audio out. In theory you could use

The synchronization of multiple zones is definitely non-trivial. Many years ago I had a few Apple Airport Expresses which had audio out. In theory you could use Airplay with these to do much the same thing as Sonos for a lot cheaper. In a one-bedroom apartment, we have 3 zones (bedroom, living room, kitchen) which are all close enough that there's a lot of opportunities to hear sound from 2 or 3 systems at the same time. With Apple it was never in sync. Small delays make the sound miserable. I finally bit the bullet and bought 3 Sonos units. They just work when it comes to the sync. There are other aspects which made Sonos far superior to just using Apple's Airplay and iTunes, but those are not covered in the patents in question. My assumption is that if getting 3 devices to stay in sync - with what I assume is UDP streams and WiFi latency hiccups - was easy or even somewhat difficult, Apple would have been able to solve it. But they couldn't. There must be some special sauce here that Sonos developed and patented.