Was it this post? Non-isolated USB sourced noise on various synths - definitely seems to be a thing - #27 by darenager
Neater solution if it works without impacting sound quality as it doesn’t require 2 USBs. Weird how some devices suffer from this and others do not, e.g. I have Peak and Hydrasynth connected to the same hub and multi-plug, the Peak is fine but the Hydra has loads of USB noise