I just ordered and set up my Roku Express but it has a constant buzzing whenever the Roku is being used, but not when something is playing. I've reset it, changed the HDMI cords, plugged it into the wall instead of an extension cord, and changed my background settings in my TV but nothing works to fix it.
Just for troubleshooting, have you tried plugging it into another wall outlet (ie another room, same room. ..different outlet). Just the device, dont bring the tv with you. Could be a matter of getting interference from from something else nearby?