Sonos is NOT a proprietary ecosystem!
I've read several articles which have that stated that Sonos is a closed proprietary ecosystem. That's not entirely accurate. In my family room, I have two 8" KRK Rokit monitors connected to a Sonos Connect (They Rok!) In my living room I have two 5" KRK Rokit's connected to another Sonos Connect, and my TV. So using a Connect or Connect Amplifier allows you to connect to most speakers. That doesn't seem proprietary to me! I also have a Play 1 in my sun room, and a Play 1 in my bedroom, for occasional listening. They sound awesome for the price point.
