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

I've tried this using several DACs and I have never heard one in which S/PIDF didn't sound significantly better than USB. I have no idea if it is due to the USB controller, noise from the power provided by the medium or what, but it definitely degrades the quality. Noise reduction devices like those from iFi can help, and I do think that some computers USB controllers are better than others, but it's still not as good as a S/PDIF inputs.

Aurender doesn’t offer I2S.  They has prioritized USB and recommend it. I have nothing to compare it with, but my N200 sounds mighty fine to me.

I prefer COAX/i2s over USB all the time , but i had the Gustard R26 for demo before and to me all its inputs were inferior to its LAN input , it sounded fuller with better stage when streaming

Regardless of input used on dac, I2S clock and power supply to that clock is the last clock seen prior to analog conversion. One is just adding more clocks using other inputs, how these clocks interact with I2S dac internal clock is variable. Employing highest quality clocks and power supply to those clocks throughout entire streaming chain extremely important for presentation. Presentation means timing, getting timing right means more analog like presentation. High end vinyl setups are the reference for this, listen to this and you'll get an idea of goal to reach for.

No