I would lay odds that the NAS is actually running a DLNA Server, the Sonore microRendu is running as a DLNA Renderer, and MC is running as a DLNA Controller having imported music from the DLNA Server on the NAS.
So your NAS is doing audio conversions, which is why DSF files are only playing up to 192KHz.
In which case, turn off the DLNA Server on the NAS, import your files from the NAS using URIs or drive mapping, and output to the Sonore via DLNA. Then MC will have some control over the audio, and you may be able to get rid of the clicks and pops, although as the Renderer, it is probably an issue with the Sonore. Also, you are going to want to Bitstream DSF to the Sonore, so in fact all audio control will be with the Sonore, and not MC.
The Sonore doesn't appear to have a DLNA Server capability, although the manual is very light on for information. About none really. Except for all the heat and connector damage warnings in the Installation section. It doesn't sound like a well-designed device, so I would be reluctant to trust it to produce quality audio.