Files streamed via Auralic’s lighting DS application sounded significantly better than the same via Roon.I'm just curious if the files were local (i.e. on a NAS or computer) or did you use a streaming service like Tidal or Qobuz?
In either case you heard the difference between the Roon player software (on whatever you were using to act as the Roon Core) and the player software embedded in the Auralic streamer. The Lightning DS app is just a control point software, meaning you made your song selections using the app, but the software doing the playback itself is in the Auralic (the App just provides control and feedback, not playback in other words).
I've had similar experiences so it's not surprising to see them confirmed by others!