Since you have Tidal access, can you switch to Tidal in Roon on your NUC, to at least keep the source the same? I know audiotroy and others say USB is generally always best, but I hear decent differences between USB and SPDIF in my system so comparing using the same interface and digital cable with your DAC would at least remove one primary variable.
That being said, and I'm a believer in tweaks making a relatively and worthwhile difference in my system, but at an almost 10x price difference in that price range if I didn't hear a BIG difference between the two, I know what my response would be; it wouldn't be trying to tweak the 10x product to sound a little better than the NUC.
@milpai, I also run a NUC with Roon and it sits with all of my noisy computer gear, but I end up running the audio stream over a MoCA 2.0 coax network and finally over fiber into the listening room right up to 1M to my endpoint and DAC (Bricasti then Mojo Audio). Maybe a $6000 server sitting in my rack would sound better, but maybe it wouldn't and I haven't felt like trying the comparison the OP just did :) If my NUC dies every few years, $500 to $700 grabs a new one with up to date hardware and my music is still carried by light before hitting my DAC...