I2S or AES/EBU. Metrum Acoustics Ambre streamer to Pavane DAC
I had that exact set-up with Pavane and then later with their Adagio. I agree that with those pieces either I2S or AES/EBU sounded best. However, for my tastes, my Mojo server and DAC connected by a short USB cable is sonically equal in every way and better in some ways. I doubt the differences are solely related to the connection method but rather the digital processing implementation, power supply, and other factors. The server uses JCAT’s highly regarded XE USB card and the DAC is also optimized for USB so, at least with this gear, USB sounds very good. This is why IMO there is no one universally superior connection format but rather it depends on how the partnering equipment is designed.