Well, that complicates things a bit... a lot really. Actually, an awful lot.
Where is MC in that audio chain?
Based on this and your first post, I have to assume that you are only using MC as a DLNA Controller and that you have a DLNA Server running on your QNAP NAS. In which case, the audio, as you rightly note, isn't going through the laptop at all, and any issues with playback are solely an issue with the NAS DLNA Server, or the H360, or the Shiit (Ok, unlikely the Shiit).
But then you are using Gizmo to control playback, so it is the DLNA Controller. I guess Gizmo could control MC which could control the NAS DLNA Server... But that seems unlikely. Is your audio path actually;
QNAP NAS <-> MC on Laptop acting as a DLNA Server > ethernet > Hegel 360 > coax digital out > Schiit Yggdrasil DAC > balanced XLR out > Hegel 360 > speaker cable > Raidho monitors
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Gizmo as DLNA Controller
In which case, your audio files would have been imported into MC using a URI or drive mapping, and not by connecting to the DLNA server on the NAS. MC would then be acting as a DLNA Server with Gizmo as Controller, and DLNA settings in MC will have some effect on the audio sent to the Hegel. If your audio files were imported into MC by connecting to the NAS DLNA Server, then the NAS is still in the audio chain, and its capabilities must be taken into account. It should just serve the files, but maybe it can do more? I don't have a QNAP.
If it is running, you should turn off the DLNA Server on the NAS unless you have a good reason to run it, such as other apps connect to that DLNA Server and not the MC DLNA Server.
If MC is in the Audio path, then the Shiit should (will) handle 24/192, but what is happening in the "> Hegel 360 > coax digital out >" section of the audio path? How would you even find out?
One would hope that it is an untouched digital path, but that could be hard to determine.
Maybe set the laptop next to the H360, connect Laptop via USB > Hegel 360 > coax digital out > etc. and see what the Shiit reports it is getting when you play 24/192 in JRiver on the laptop, check the MC Audio Path to confirm what it is sending. Oh wait... the shiit only reports Sample Rate with its lights, doesn't it? So it can report 48x4 or 192 KHz, but it can't report the bit depth. I guess you will have to rely on what the MC Audio Path says it is sending, and assume that there is no transcoding in the "> Hegel 360 > coax digital out >" section of the audio path. Unlikely I guess. But what effect, exactly, would this section of the audio chain present to MC as?
In fact, what does MC see as the output audio device? The Shiit, or the Hegel?
I would hope that the output Audio Device MC sees is the Shiit when connected via USB as above. When connected via ethernet MC would have to see the Hegel, as it is the network endpoint, which means DLNA Renderer in this case. But then the MC DLNA server would see the Hegel Renderer (including the DAC ) capabilities when it is actually playing to the Shiit DAC.
Lots to think about and test. Maybe some questions to Hegel about that "> Hegel 360 > coax digital out >" section of the audio path.
Maybe test this audio path to see if any of your playback problems exist in this configuration:
QNAP NAS <-> MC on Laptop acting as a DLNA Server > ethernet > Hegel 360 > speaker cable > Raidho monitors
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Gizmo as DLNA Controller