Does your DAC sound better through the S/PDIF or I2S inputs than through USB?

For a long time I used a Windows NUC driving my DAC through USB. (A modified Gustard X20Pro.) Then I got an Aurender N100 which provided a better USB source. I also tried a DAC on the recommendation of a friend in the New Jersey Audiophile Society. People were excited about this there: the Gustard R26.

I found that the R26 is disappointing through its USB input, but excels through the Coax S/PDIF input using a Gustard U18 Digital/Digital Convertor.

This probably points to a subpar USB implementation, to be honest, but I started wondering if this is a general pattern among DACs that can take both S/PDIF and USB.

Anyone find something similar in their DAC?

For example, I'm interested in a Schiit DAC (not sure which model yet). Now that I have the DDC I can drive it through Coax and compare to USB. With the Gungnir 2, I may not have the choice of USB because they have a USB C connection and my only good USB cable is A to B.

Note: what is wrong with the R26 through the USB input: very light bass, unintegrated treble (sibilance kind of clouds over the sound and doesn't integrate with the body of the instruments)