I have the Gustard X16 and love it. That said, I suspect that it would not be easy to hear a difference between the X16 and D50s in a level-matched blind test.But I get where you're coming from wrt build quality, heft, etc. My only gripe with the X16 is the tiny display, but that probably won't be an issue for your setup.
If you don't mind dealing with TRS to XLR cables, I'd also look at the Topping E50 (same DAC chip as the X16…I have this one too) and D10 Balanced. I've really been impressed with the E50 so far. Only niggle is that it takes a couple of tries to get it going after a cold boot when streaming to it via a Raspberry Pi using Roon.
Have you an opinion on sound quality (Topping E50 vs. Gustard X16) ???