TVs, telephones, smart phones, iPads, all of that kind of stuff is bad for the sound even when there’re not (rpt not) ON. That’s one reason why the sound is frequently so bad at shows, you know, with everyone standing around with smart phones in their pockets. And why demos sometimes fall flat on their faces. 😛
Since TVs probably dump a bunch of rf into the house AC and perhaps into the room, too, you could try a large ferrite on the AC cord and see if that helps. That’s a large ferrite, not a large ferret.