Nothing earth-shattering, IMHE. Compared to speakers, tubes, or TT, DAC differences are at best flavoring. I compared a $250 Topping D50III with a $5K Holoaudio May 2 DAC, and while there were *slightest* differences, one was not objectively better than the other. For some recordings I liked one better, for others the other. And I did a side-by-side comparison, having both plugged in, grouped in Roon, volume matched, so could switch back and forth on preamp for instant comparison.
Differences in recordings are greater than differences between delta sigma and RR DAC, so differences between DS DACs are even smaller. The is confirmed by comparing on headphones the Dragonfly series (red, black, cobalt). I had difficulties convincing myself that I heard any differences. This is at the low end of price spectrum, where one would expect the greatest improvements.