Recommendations for Blu-ray Player

Google shows NO hits for AmazonUHD app except for this post. No clue what you're talking about.
And why would you want a quality audio streaming service on a video player?
Nobody else does so you'll have to build a one off.
Easier and cheaper to get a streamer.

I would simply get a Roku or Amazon Fire Stick and keep your Sony for discs. A smarter and much less expensive alternative, and tons of streaming options available to you, including Tidal. Heck, most smart TV’s can steam what you want to via apps.

@fuzztone AmazonUHD = Amazon Prime Music Ultra High Definition it's kind of like Tidal Masters or whatever other HD streaming services are out there.

@bkeske think those devices have HDMI out only. For audio, I need it to be coax - the HDMI will connect to a TV for watching music videos (concerts, etc.) Also, I only have one coax input to bring in all the audio, so all content needs to be on one coax output, rules out the TV option.

Blueray players seem to be few and far between these days. Like the previous responses, I don’t think there’s anything on the market that would be a blueray player AND have the Amazon UHD app/capability with a coax out. 
I was thinking you could utilize a Amazon Fire TV Cube with HDMI routed through a receiver (for audio playback) and then to the tv (for video), but even then, Amazon limits their audio stream to 16 bit...

Curious myself if there’s something out there that fits your needs. Interesting situation.