Having the same issue with Synthrotek Super Power supply. For now, solving that by powering ansible by spare uZeus, without anything other attached to it (if e.g. power ansible and mixer or vca from uZeus – there will be buzz when grid is connected).
Maybe power regulator converting +12V to +5V to power grid generates this noise and feeding it back to power rail? I don’t know.
Going to try noise filtering busboard soon, and hope that capacitors on power lines will filter this.
I think ideal solution would be to get monome switch, wish they were still available.