Maybe it depends on your TV. A few modern TVs have two audio out plugs one that kills the speakers on the TV and another one that lets others hear the remote set volume, and headphones with their volume settings. A lot of modern TVs only have one one audio out plug Kills TV Speakers, and one digital optical output that requires the following for TV speakers and Headphone operation:
The Sennheiser RS 175, RS 185 and RS 195 Wireless Headphones have the ability to connect directly to a digital optical output that is outputting a PCM signal (most TV will sense this or provide a setting with the remote).
Orei DA34 Digital to Analog Audio Decoder is what Sennheiser suggests.