To enjoy the full benefit of hearing TV audio through your Bose® system, turn off the internal speakers in the TV. The TV may have an onscreen audio menu that includes an option for turning the TV speakers on or off. If the TV provides both fixed (FIX) and variable (VAR) audio output connectors, use the fixed connectors for higher sound quality.
Newer TVs normally have a setup menu item for turning off speakers. Older TVs may have a speaker on/off switch on the rear panel near the audio output connectors.