Just a thought...
Do you have a computer, wireless internet or a cellphone nearby your home theatre room. Could this cause any type of interference/hum with the subwoofer/home theatre system?
House, it's funny you mention cellphone interference. When I got my new electric wheelchair earlier this year, it came with two warning tags (that weren't supposed to be removed) stating that a cell phone should not be operated around the wheelchair because it can cause the wheelchair to drive out of control. Pretty absurd seeing that it's virtually impossible to not be around a cell phone that isn't in use these days.
