I had an Ares II fed by an Iris and when I added the Iris, there was a noticeable improvement .
*note - my Ares II didn’t even have I2S and it was still and improvement.
Also, when using my 30 year old California Audio Labs Sigma II tube dac, the Iris helped it in a few ways. (1) It stopped the relay from triggering when skipping tracks while I’m streaming and (2) more importantly , it just brought more clarity and detail in the sound.
All that said, I sold both the Ares II and the Iris and now I’m just running coax Spdif into a Border Patrol dac from my streamer and I’m happy as a clam.