And I bet there isn't a DAC on the planet that doesn't sound better with ferrites on its electrical SPDIF or USB input.
The mystery for me is why it's taken so long for this perspective to appear, given that RF isn't a new problem. At least I ran my 1990s DAC with an optical connection (AT&T, not TOSLink), so didn't suffer RF on the input cable in that case. But I ran my Hugo TT in the belief that the galvanic isolation on the USB input solved the problem.
I think we have to discard galvanic isolation as an indicator of quality. The change with my DAVE on its galvanically isolated USB that came from adding ferrites is of the instant WOW variety.