Last night signed up my X50Pro to Amz Music (have HD service), had to use Music X Neo app for it but works like a charm. Was browsing extensively trying to find in song with higher than 44.1k sampling frequency, no luck so far. But all music is in 32bit resolution, that's double comparing to CD. And yes, most of it sounds stunning, super clear, detailed, similar to my hires files I listen offline. Whether Celine Dion or well know A-Ha, I could not resist turning around to check unit display "what is that makes sound so good".
I also tried Group Play. It is new function that allows employing multiple X50s to play same song in sync in multiroom. Indeed it does exactly that and in perfect sync. No delay or lag noticed. One problem is for some reason my other X50D stops playing via USB Audio when group mode is enabled, I have to switch to coax output to get the sound. My X50Pro does not have this issue, plays via USB no problem whether in group play mode or not. Must be X50D software glitch which I reported to Novatron tech support.
Btw, the latest firmware available at Novatron website I used (r1688) to flash my old X50D to enable Group play, messed up the UPnP service. I am unable to access X50D library from X50Pro by Genre, Album, Artist. Only selection by song Title works, but that takes forever to display results (over 10,000 songs in my storage) so it's unusable. This did not make me happy either about new firmware, so beware to use it.
Hoping Novatron tech support will repond soon or I have to roll my unit firmware back to factory giving up Group Play function between both X50s.
That's all for now. Cheers.