I modded 3 different Audio Note Dac's. Very similar modular design and NOS non-digital sound.
Rolling that Audio Note Copper coupling cap will result in dramatically different sonics. Way more than tubes in my experience.
The rest of my system trends toward warmth so the AN Cu wasn't the optimum cap there for me.
The problem with dong this is expense, and the time it takes for the caps to burn in.
Anyway, I've moved on from AN to ABBAS which has shares DNA with SW1X. Having fun with more mods and replacing caps with Black Gates as I can find them. Would love to hear these SW1X's someday... I have a feeling I would like them. Although me thinks to beat the ABBAS it would be north of $6k.