Mofi 
most of my Bluesound issues related to not all 4 of my units in the house successfully updating in sync.  The Bluesound updates were frequent and occasionally one player would get hung up.  That somehow led to all of the players failing, and would require calls to Bluesound.  My main system is my 2 channel system and the Vault2 there has been superseded by a Bryston BDA-3, but I kept the Vault2 in.  My other systems have Node2 players.  Life has been quiet in my Bluesound Universe by refusing to do updates, and it isn’t worth disturbing the peace to add Amazon.  I’m pretty happy with Qobuz.
Just realized that Chromecast audio doesn't send out Ultra HD via toslink (downgrades to HD or Standard).
This really grinds my gears...grrrr...
Don't get stressed about that, bstatmeister. Unless you are trying to listen to a recording that was originally recorded in the studio in 24bit (few are), there is no quality difference between Amazon's HD and Ultra streams - a fact Amazon deceptively does not mention.  And forever, it seems, Redbook CD recordings (16/44.1) have been referred to as "standard definition." Amazon has, in an equally deceptive decision, decided that their "CD quality" streams are now HD.  Just listen to HD, enjoy it and don't fret over Ultra.
My nephew has worked for Amazon for years, presently working on some "top secret" stuff with one of their R&D labs.

I sent him an email, with the Roon links, so if he knows someone who works over in the Amazon Music HD group, he (hopefully) will let them know of us audiophiles' interest in integrating the service with Roon.

I hope it gets the ball rolling.
I need to update my experience with Amazon Music.

It was essential for me, in order to get the best sound, to manually adjust the sample rate on my control panel in windows streaming Amazon Music through a laptop and Audioquest Red Dragonfly.  
The sound quality went from really bad (worse than mp3) to really good.

I’ll have to listen some more and check out the music selection a bit more but Amazon Music jumped from last place to a possible first place for me.

Exciting stuff!