Hard drives (“spinners”) typically rotation at 7200 rpm, and this generates vibration. Placed on surfaces like concrete flooring, this is of little concern. But placed on a hardwood desktop or floor, those vibrations can resonate into the material in a quite annoying way (a low humming vibration typically). Or not, depending on the material. While the enclosure can eliminate much of the vibration, certain frequencies are not attenuated.
MPG has both a hardwood desk and hardwood floors, so these types of vibrations are very unwelcome, hence a search for a solution.
The Auralex MoPAD Monitor Isolation Pads @AMAZON do the job. While designed for audio monitors (speakers) they do a great job of blocking vibrations from spinning hard drives. The pads include wedges that allow the hard drive(s) enclosure to sit perfectly level on desk or floor.