I suppose we all have different experiences.
I couldn’t hear the slightest difference between Naim app and Roon with my previous system. (my system was a full 500 DR series system, ND555 with two 555PS, Super Lumina full loom, dedicated mains, etc. And Magico speakers).
The PCM data sent in RAAT by Roon sucks the music out, but if the streamer downloads the music and extracts the PCM from the flac, or if it comes via UPnP in some wrapper, it’s all fine 
Oh no, more A/B testing to do?
Or listen to music 
I’ve no idea what that means. How does it relate to internet streaming or a local stream via WAV files on a Uniti Core to the NDX2 via Roon?
I just want to stream and enjoy my music in good quality without confusion….
What it means is that it’s the same data either sent by Roon as raw PCM via RAAT (which is not so much different from UPnP as a transfer protocol), or it is sent by a UPnP server via the UPnP protocol either in a WAV file or in a FLAC file that the streamer decodes, or the streamer downloads it from Qobuz as a FLAC and decodes it, and in all cases the same extracted PCM data with the music samples then goes into the SHARC processor and the DAC.
The exact technical data handling in the streamer differs slightly in each case, but it’s laughable that one of them is supposed to suck the music out.
If you like the Roon interface, just use Roon and enjoy the music in good quality and without confusion (and there is no need to mess with its DSD settings either unless one is so inclined)
I think I’ll upgrade me record player…….
Well I never really understood how the vinyl groove encodes stereo 
Me neither 
On a more serious note, the one thing I haven’t done yet is compare a Qobuz hi-res internet stream versus purchasing the hi-res file and playing via my Uniti Core. This is probably what the OP is about. What was the conclusion on that before I go buying any to test?
Although I see I have a hi-res file of Steven Wilson’s Hand. Cannot. Erase on 96/24 and Qobuz has the same, so I’ll go compare those and report back.
I downloaded Dylan’s Shadows in the Night hires from Qobuz (very nice recording and fab album) and as you would expect from me, I can’t hear the faintest difference playing the stream or the file via Roon.
As you would also expect, other people hear clear differences although there is no plausible cause for any difference.
The main reason is that you have a strong, reliable network. Some folks who can tell the differences because there are some problems somewhere in their own lan or the ISP, I guess.
I personally do not hear any diffs.
Which problems would have this effect?
Inter frame window gaps, retransmission of lost packets. I know buffering of network packets can mitigate it, but to some extents.
But Roon and/or the streamer buffers it anyway
Roon buffering is finite. In realtime, practically it can take minutes to recover your stream if retrans happens, sometimes you can lose some network packets forever.
Sure, but quite large. I doubt that people’s typical internet connections routinely fail to get a packet within a few minutes for a rather low data-rate stream.
Edit: saw your edit, but really, in practice? People use stuff like Citrix in home office, works as well normally
Indeed, alas, I couldn’t discern a difference. A very well recorded album and both streams sounded excellent.
I have found a bug of sorts with Qobuz on Roon though. Roon is not showing all Qobuz versions of albums that show within the Qobuz or Naim App. The example was Pink Floyd’s Animals which only shows as CD version on Roon, but Qobuz shows a 24/192 version on their app. Annoyingly, the Naim app doesn’t even show the stream rate until you play an album.
TCP is a reliable network protocol, right? Not true! What happens is that when the stream gets to an unrecoverable state, the TCP connection will be severed, and the reconnection happens, and that will have an audio impact.
Hmm, I never look in Roon. May the hires be new on Qobuz? Roon always needs a few days to get info about new releases