I would try my 3M AB7050HF absorber tweak and get them off the same AC line or circuit breaker.
Plus get any of your audio system power cords away from fan controller.
I modded my MC2500 amps to reroute its internal AC lines away from fan control. McIntosh figured that out when they built follow on MC2600. Much quieter.
There are many tweaks in this thread to reduce noise floor.