Just wanted to share a finding with you, regarding the use of Roon (Rock) in combination with a SOtM sMS200-Ultra and DACs by RME.
Files above 96kHz/24bit did not play back, although the VU-meters showed “music”, but no signal apart from a faint crackling sound was audible on the outputs of the DAC.
In my case, the DAC was RME’s FireFace UCX II. I set it up in Class Compliant (“CC”) mode, so that the sMS200-Ultra was able to recognize it. All hardware had the latest firmware installed.
Roon itself does not automatically “know” about the UCX II, RME is not listed in the audio setup dropdown-list. It will show up with its “internal naming”, but Roon does not automatically apply the appropriate settings for it (as it does with units stored in its database).
Apart of that, knowing the specs, in Roon, I set the UCX II up to max 192/24, stereo, downsampling as needed, no MQA. Interestingly enough, all content up to 96/24 played fine, above that: only faint crackling noise, nothing else.
After directly attaching the UCX II (still in CC mode) directly to a USB output of my NUC running Rock, Roon automatically set it up as “7.1 channels”, “send stereo/mono content as 7.1” and “swap rear and surround channels”. The UCX II played fine up to 192/24! No more crackling!
Hooking it back up to the sMS-200 Ultra, I recreated these exact settings and to my suprise: everything is smooth up to 192/24 as well.
Reason for this seems, that the UCX II presents itself as an 8-channel “multichannel” unit and must be adressed as such. Adressing it as a stereo unit strangely enough only works up to 96/24 - whatever the reason may be.
Bottom line: should you experience distortion or crackle-problems with RME DACs, experiment with various channel-count settings. Some of their consumer-products are mere stereo units, some may present themselves as 4-channel units etc.