Apologies for the belated reply - and a thanks to all who replied. Alternating between USB ports/cables/devices/computers yields no differing results with regards to the buzzing. However, unplugging the USB cord completely culls the sounds. I also wish to make an amendment to my original statement where I mentioned the device makes no noise when the PC is off; it does - however, it is even more feint, where one has to essentially rest their head against the unit to pick up on it.
Furthermore, I've been turning my device off at night via the power toggle on the unit because of the incessant sound of the buzz. Is cycling power like this daily going to negatively affect the lifespan of the device?
And fwiw, the unit has been wonderful in every regard despite this buzz. The parametric EQ has complimented my 800S beautifully.