I got this on another forum

"Those settings are for the "offline listening" downloads that are tied to your Amazon Music / Music HD player and streaming subscription. Cancel your streaming subscription and they're gone.

Purchased downloads that you can keep permanently come from the regular Amazon store, in MP3 only. From Amazon's perspective it's natural to cross-sell, but I think a lot of customers are going to be confused and unhappy


.

so even though in Amazon HD you have the option to select HD downloads after you purchase a song, you only get an MP3 file when you do it
I've been using my laptop pc via usb to my dac and compared with Qobuz, Amazon HD does not sound harsh but the sound lacks substance.  Seems too thin and polite.  No punch.  Voices and instruments do not have that palpable presence.  Qobuz is better in that regard but the sound is bit harsh and more digital like.  What do you guys hear?  
I am on vacation now and so I will have to wait until I return to try it on my Bluesound gear.  I currently stream Qobuz through Bluesound and it’s a very good quality but I find subtle differences between that and both CD replay or ripped CDs played back via Bluesound, so there is some room for improvement.
i currently use the limited Amazon streaming that my Prime Membership buys but it doesn’t do well with hapless playback.
  I do wonder at the economics.  Amazon has the cash reserves to take a loss on this but once they have driven the the high Rez streaming competition out of business can raise the price through the roof