Curious to hear the quality. I use Amazon for movies and, even though they are "HD" sound, the sound quality never seems to be as good as when I play the same movies using blu-ray or UHD blu-ray disks.  

For movies, I assume there's compression, dithering, or whatever going on there.
While streaming, to me, is entirely viewable and listenable, I still get Blu-Ray discs from Netflix specifically as my understanding is that, regardless of the speed of your internet service, streams will always be of lower overall (audio and video) than BR discs.  

But a better reason is that the newest movies are only available from Netflix on disc.

But this is really an entirely different subject.
This is not hi-res quality music. Most songs seem to be redbook cd quality. Hi-res quality can be 24/192, but DSD and MQA are of much better SQ. Since I have hundreds of DSD or 24/192 songs ripped, and also stream Tidal MQA, I use roon. I will never use USB to connect to an external dac so I use Roon server on a Mac and my PS Audio DS sr dac is accessed using wired Ethernet. Right now, nobody else has perfected using Ethernet going to a dac. As soon as Roon has an update to gain access to Amazon so I can compare an Amazon HD song to a Tidal MQA song, I’m happy with Tidal

Like @rbstehno I was disappointed to find out that I could not stream Amazon music files to a UPNP renderer.  I worked hard to get off of USB and that's a deal breaker for me.