If you mean a hum, not a buzz, it could be a ground loop. You could experiment with different household circuits, different plug orientations, if any use a two prong plug (without the ground pin), a ground lift if you have that on the RME.
If you do mean buzz, that can be caused by very dirty power, often from dimmer switches half dimmed or some fluorescent fixtures.
A three pin to two pin power plug adapter can be useful, but you will never hear it recommended due to potential shock hazard.