It's also great for radio, if you have two Alexa device. I've got an Echo Dot connected via the line out to my 2012 Denon receiver, and when I'm not watching TV I leave the Denon on that input. The Dot has its microphone turned off so it can't hear commands.

I've also got an Echo Show in the same room with its microphone enabled. Then I can just ask Alexa to, for example, "on Dot, listen to classical KING FM, on Dot", and the Show will tell the Dot to start streaming that.

(I say "on Dot" at both the start and end because sometimes it wants it at the front and sometimes it wants it at the back, and I was never able to figure out what determined which it wanted at the moment).

Oh, and it is also a great way to get Spotify to play through my receiver. I can use the Spotify app on my phone or tablet or desktop to queue up things but tell the app to use Spotify Connect to tell the Dot to do the actual streaming of the music.