It depends on the quality of the USB controller. I've seen some devices (Raspberry Pi) where it seems to make a lot of difference. I always go optical or Spidf whenever possible.
Usb or Optical
Have a custom built computer has latest greatest Realtek Audio 1220 vb or whatever its called. I have a Little Dot Mark ii tube amp and i just bought a SMSL D300 dac. Should i go optical from computer to desktop dac ? or usb from computer to usb on back of destop dac ????? im not trying to get dsd or any crazy hi res 24/192 is fine. Whats going to give me the best sound ?
thanks for all input is welcome.