Best Digital Interface

@kennyc, I think you're right to separate out "Best Digital Interface" and "Best Digital Performance." Best digital interface is only one consideration, while best digital performance will take into account any strengths in our particular streamer outputs and DAC inputs. 

This summer, I was planning to built a Pi and run USB to see if I heard a difference with my Async DAC. From here, I would like to include a reclocking hat and run SPDIF to again see if I heard any difference.  

Apples to oranges apt description. Many if not most dac manufacturers optimize usb input, starting to see I2S implemented more often. I2S theoretically better, implementation is the key. I've found maximizing streaming experience is extremely complex. My streaming equipment chain is almost certainly one of one in the entire world. Perhaps the future may bring more certainty to best interface.

During the 90ties and 00decade, i enjoyed a wadia x32 by spdif with a micromega Duo CD 3.1. Since 2013 my preferred dac is a Mytek DSD 192, using the FW-Output/Oyaide-cable! First, i used a windows-PC/Windows 7 Pro with a FW-PCI-Card.
Since 2020, i've got a streamer by apolitan.de and a PCIe-Card/Chipset by NEC (TI no longer avaiable), on going using the mytek. Comparing to a PS Audio DSD, i'm very satisfied by the mytek/no upsampling.
Frontend by ATMASPHERE and high efficiency speakers (4way-full horn), you can hear every breathing! Are there any other members with similar experiences?

@hgeifman --

The answer is very simple.  You have to listen to your system, using various cable connections and decide what sounds best to you.   There is no correct answer for everyone.  

+1

I decided on a music streamer with BOTH USB and AES/EBU digital outputs to my DAC.  I listened AND listened to both USB and AES/EBU connections for several weeks.

After weeks of switching back and forth, I prefer the AEB/EBU connection from my Aurender music server to my DAC.   To my ears, the music sounds slightly better using the AES/EBU Connection.  

For over 13 years my source has been PC-based/HDD; I've used a DIY audio server with AES/EBU output via an RME soundcard, then a USB to S/PDIF converter, then a streamer solution by SOtm, then re-visiting the USB to SPDIF converter (Audiophilleo + PurePower), and now back again essentially to where I started - an AES/EBU output, this time via a Marian Seraph D4 pro soundcard connected to the XLR input of my DAC/preamp with a braided Mundorf Silver/gold digital cable. Even with the DAC clock-slaved by the Marian card it's my preferable sonic scenario.

With this AES/EBU connection the music is presented less congealed, more effortless/unforced, and just slightly fuller and better balanced throughout. 

@phusis - you should try a Pink Faun AES/EBU card (as long as you're not running Linux on Intel cpu).  You can even get it with upgraded OCXO clocks.

I know the Marian Seraph is likely a very good card, but it's geared towards pro audio where you need a ton of digital outputs, lol.