Ok, have a bit of an update on this. I found the following discussion in the HifiBerry community:
Coincidentally, I just updated my HifiB’s to the latest OS today, 20210203, and it definitely did something. Now when I play 192 content, with Roon re-set to max of 192, I hear a loud pop when the track starts and then I hear a constant chug-chug-chug (think train sound) while it tries to play the 192 track. Switching back to <192 content works fine, and setting Roon to a max 96 and it correctly plays the downsamples 192 content. So to me this means it’s def not a cable issue, it’s something to do with the Digi+ Pro.
I don’t see any notes in this latest OS version on the HifiB git repo, and unfortunately I’m currently not able to log into their community to post my findings, but wanted to share an update here.
Still odd…even odder that it’s working for some on this thread with what looks like the same audio path and same devices. The mystery continues…