A:Answer You do not need to use both. It will connect to the internet (or your NAS device with stored music) wirelessly.
If you have multiple speakers in multiple rooms, you can hardwire one or more to your network router. The benefit of this set up is that the Sonos speakers create their own wireless mesh network, so you can extend the speakers further than your normal wireless network can reach. Also, it moves the traffic off of your wireless network onto the Sonos, and the internet connection remains stable through a wired connection (no dropouts in sound, but in my experience those are rare/non-existent using my wireless network anyways).
