First, try recording with either... all appliances in the area shut off, including the monitor. See if that helps. If you're still getting hum and you're playing on a strat or another guitar with single coil pickups flip the pickup selector switch to a position that will activate either two single coils, or a humbucker. For example... if you are currently playing through the bridge pickup alone... switch the 5 way switch to the next position up (bridge and middle activated). If you have a humbucker equipped guitar... or the stuff that I recommended above doesn't work... check out a noise gate. It will help out a lot.