Of the many DAC's we tested, The USB connection was always inferior sounding compared to the other inputs (i2s, AES, coax and optical). The i2s input seems to be slightly better on some DAC's.
If you have a streamer that only outputs USB I would recommend a good DDC to convert the USB to ether i2s or one of the other outputs. A good DDC will strip, rebuild the clock and clean up the power from the noisy USB output. This makes quite a large improvement in sound quality. Jitter and noise is your enemy here when using USB. If your streamer outputs i2s, AES, optical or coax I would use one of them (Most likely no need for a DDC). If you want to output higher resolutions of 384 kHz / 2x – 4x DSD or higher you would need to use the i2s as the other outputs only support up to 192 kHz and 1x DSD.

