Noise from Midihub regardless of Config

I’m getting audible noise from my midihub.

The noise is an audible buzzing from my monitors. It only comes in when my Midihub is plugged in and on.

The noise does not exist when I just use USB connections between my controllers and synths, or when I directly connect my synths to my controllers via a single midi cable.

The entire rig is powered via the same power conditioning unit, including my PC.

Hi, is anything connected to Midihub via MIDI when the noise occurs? Does the noise still occur if you leave only Midihub connected via USB (and possibly your USB sound card if you’re using one?)