can't connect transmitter to TV

Sometimes TV Boxes (ie the thing that decodes a satellite or cable TV feed) have their own audio output. I'm in the same situation with my LG bedroom TV but fortunately my Virgin Media TV Box has its own optical output that works perfectly with my Avantree Opera Headphones/Transmitter. If you don't have a seperate TV box and only watch the terrestrial channels that your TV tunes to directly then maybe the TV has a small 3.5 mm headphone jack tucked away somewhere?