+1 for the Denafrips Pontus II DAC, though I have not heard the Gustard. I'm also a little over a week into testing a Denafrips Iris DDC feeding the Pontus, and yes does it make a very noticeable difference.......from a Node 130. Cost of the Pontus II and Iris DDC is $2,300.....I should get a report out this weekend or early next week.
I also can recommend the Holo Audio DACs, but they'll run you even more