If you've got hum in the system, don't try and hide it - Fixt it. Call in an electrician if you have to, but track it down and take care of it at the root.

Most often, the hum is caused by a difference in ground potential. You need to be sure that the entire sound system is all on the same circuit. This includes amps, outboard, everything. If you have to run extension cables then do, but it is important to do this. Try to run this from a clean circuit as well. One that is dedicated just for audio and nothing else, especially lighting. Hope this helps.