I seem to hear some differences in sound after this change. Feels like it is some sort of disortion in some passages. Especially in big keyboard passages, with synts, mellotron and alike.
Maybe it’s my imagination.
Have others noticed something like this?
I personally would not trust my own audio memory. Plug in the old unit and have someone else blind test you.
Or, recheck everything…
The digital parts of the stream are not changing. If you hear something, it’s either past the NUC in the signal path, or the new NUC is somehow creating fidelity changes in something further down in the analog stage of the game. Remember, Roon doesn’t/can’t mess up digital and it doesn’t play with analog. That’s up to your DAC and everything after that point in the signal path.
Digital errors sound like glitches, not subtle fidelity differences. You can’t confuse the two.
You failed to tell us anything about your setup, so those are about as generic instructions as you’ll get.