I’m afraid the grounding didn’t work for me either.
As much as I liked the unit, and especially the pre-amps, I ended up exchanging it for something else because my retailer is out of stock and back ordered on UR22’s.
The Akai EIE Pro I got has no buzzing whatsoever. The pre’s are not as sweet sounding but they are still good, and for the extra $100 I got a USB hub and more inputs.