I was not able to find the user manual but you should check that and find the line out connection as that's analog and what would go to your transmitter.
Where we are renting, there is a RCA LED40G45RQ TV hooked up to Direct TV via HDMI. We have an old RCA infrared transmitter that transmits a signal to our pair of headsets. The IR transmitter hooks up to the TV with either RCA red and white plugs or a 3.5 mm jack. I've read that with that TV I need a digital to analog converter. What kind of description should I input to find the converter I want? Or can someone recommend a brand? The ones I've found seem to require a coax input. Thanks, Bill