DAPpower
1000+ Head-Fier
what clock cable are you using for connection to X26 Pro and U18? I am a X26 Pro and U18 user as well, on my system, both U18 and X26 Pro on EXT clock provides better resolution and soundstage with no downside. If your U18 sound more surgical overall with EXT clock, it may be an indication that you are not using a suitable cable for clock connection to U18. FYI, I am using 2 different clock cables for connection to X26 Pro and U18, what is good for X26 Pro may not be good for U18.
I'm using 2x Harmonic Digital Copper III for both X26 Pro and U18.
What cable do you think would be more suitable?
My budget is super tight right now, hopefully it's not something I can't afford.