Sonos owners know that one of that speaker's killer features is the ability to stream audio throughout your house. Amazon just co-opted that with Multi-Room Music for its Alexa-enabled Echo smart speakers.
Now, people who own multiple Echo devices can group them together in the Alexa app, and have them play the same music stream throughout their home.
There are a few caveats to this service. Currently, Multi-Room streaming works only with the Echo, Echo Dot, and Echo Show. It doesn't support the Tap, or any other third-party Alexa device, such as the Fabriq or Omaker Wow. Also, you can't use the Echo Dot's Bluetooth connection with this feature, so you'll have to plug a speaker into its 3.5-mm jack instead.
Lastly, multi-room streaming only works with music, and not such things as Flash briefings, books, or skills—which includes Sirius. However, you will be able to stream music from built-in sources, such as Pandora, iHeartRadio, and TuneIn (Spotify is coming soon).
Those who have a Prime Music subscription will be able to stream just one thing at a time to a group of speakers. If you have Amazon Music Unlimited with the Family Plan, though, you can have several streams going at the same time.
As with other Alexa features, expect the functionality of Multi-Room Music to increase. Amazon is also releasing APIs so that other connected-speaker companies (such as Sonos, Samsung, and Bose) can also control music playback using Alexa. Amazon is also releasing an SDK so that third-party speakers can also be used with Multi-Room Music.
The addition of whole-home audio streaming should help keep Amazon one step ahead of the competition, especially in light of new smart speakers, such as Apple's HomePod, coming out later this year.