In my experience, it’s simply possible for audio over USB to experience interference in some scenarios. Eventide doesn’t necessarily have any power over this, and the culprit is usually the cable which acts as the “antenna” picking up the interference. The quickest way you can try to mitigate this is to add a ferrite bead to your USB cable. You could even add two of them (one at each end of the cable). You can get a big pack of them in different sizes online for pretty cheap and they just snap on to the cable. Takes two seconds.

Maybe the Eventide staff here could answer, but how important is it to use a USB 3.0 port for the H90? I understand the unit itself has a USB-C port, but is there actually any performance loss if you connect it to a 2.0 port on your PC (assuming you have a PC with one available). USB 3.0 is actually somewhat more susceptible to interference than USB 2.0 due to its 5gbps broadband frequency overlapping with the 2.4Ghz wireless spectrum. Slower USB 2.0 doesn’t have this problem, and some devices actually recommend specifically using a 2.0 port because the faster 3.0 speeds aren’t necessary and you can avoid the interference issue.

Not sure if this is viable for the H90 though. It might need the 3.0 speeds.