Am listening to Amazon Music HD with Airplay into my stereo/AV rig using the app from my iPhone or iPad. (Airplay will deliver Red Book audio and the network adapter supports mini plug and digital out.) I’ve A-B’d several CDs vs Amazon and can’t tell the difference. I do find that when some recording are labeled “remastered” the sound can be distorted and/or compressed. May be the Master selection issues others have noted?
Keyword search in the Amazon app can be problematic sometimes. Keying in “Jarret Shostakovich” should find his recording of the piano preludes and fugues. It doesn’t. Etc. etc.
On a side note, I’m using the same setup to stream Roon. 1200 CDs imported to ITunes using ALAC. Roon server on my Windows PC uses the iTunes repository. Roon app on iPhone and iPad. Again, A-B a CD and can’t hear the difference. (Although I can hear the difference between AAC and ALAC encoding.)
Streaming has changed how I listen to music - in a good way. I do miss liner notes, tho. I like to know who played, engineered, and mastered the recording.