Steinberg Support answered me that with the only one returned unit for this reason of noise, they did tests on multiple machines and don't have the problem... They said that in similar cases they had seen, including other brands, the cause is usually on a specific system and caused by computer's USB power system.
If could be an USB power issue, why some customers did the same tests with other brands USB-powered interfaces and there was absolutely no noise? Only happens with UR22... Maybe UR22 requires a best USB power than the other brands.
Have you tried on others desktop and laptops?
If that's the case, especially for desktop PCs (and even Laptops), I would pay particular attention to the PC PSU.
Budget PSUs are an ailment to audio PCs - introducing ripple noise harmonics and shortening the life of components (Can you say D e _ _ or H _).
Higher quality active power correction +80% PSUs are the only ones I use in desktops. There are budget power
bricks available for Laptops with inferior components that will not provide stable power day-in & day-out.
60 cycle hum filtered for your listening pleasure!
I always test the output voltages on all new PSUs; e.g. 5v output (+/-) 5% = 4.75v to 5.25%. But, that's just one part to be concerned over. A PSU is as important as a Preamp in today's digital world.