Ground Loop Noise with Usb Microphone

Are you monitor and MINI plugged into the same power supply, not separate outlets?

Things to try... except for the keyboard/mouse and Mic, unplug all other USB devices, still hum?

or, with everything plugged in and the hum audible, turn off the monitor, then unplug the monitor's power cable. still hum.

Here in the US, with special cases we have to use a ground lift adapter, three to two way, it's not advised as a power supply short can shunt current to external parts of the device.

In my experience, it's usually an electricity issue with something other than your microphone. Try plugging your mac into a different outlet. If you can, move your mac to a different room and test your connection. Try unplugging different USB devices and see if one of them may have been the cause of your noise.

Get a decent mic.

But then - if it goes to 2000kHz, it can't be that bad.

That's pretty high. Almost over one's head.

Ok, I'll phrase my initial suggestion differently: has this ever worked with this particular microphone ?