I was perfectly satisfied with my Node 130 using USB to my Denafrips Pontus II DAC. Started reading threads like this, and after checking with Alvin Chee at Vinshine, I decided to add a Denafrips Iris DDC between the Node and Pontus.
The Iris optically and galvanically cleans and re-clocks the data, and then outputs via I2S to the Pontus. The sound improvement was immediately noticeable even before the Iris and cable had a chance to settle in. Why I keep reading these threads