No experience with the Audio-GD DI-20HE (it looks awesome, btw!), but I have successfully used a Holo Audio Red in DDC mode, feeding it USB to convert to I2S for a Pontus II. I have the Iris as well, and it's great, but I was curious about I2S output at 768k/24, which the Red supports.
Both the Audio-GD and the Red have adjustable pinouts, and the Denafrips DACs also have adjustable pinouts, so I suspect you would have no problem.