I suggest you hook up the audio cable from your samsung receiver to your audio\video receiver and use your stereo for sound. TV speakers are not that good when compared to quality speakers. If the samsung is a cable or satellite box, connect it to your AV receiver. You may have to go into setup and set the audio to digital output, (optical, spdif, PCM\Dolby Digital). Digital audio goes by all the previously mentioned.
video receiver=cable\satellite box
audio\video receiver=stereo receiver with video switching
Laurie, that optical output works only when you are viewing a digital channel either via the TV's internal ATSC tuner (with appropriate over-the-air antenna) or from the TV's HDMI input fed by a digital source (with a digital audio signal present). See pages 11 and 39 in your owners manual, where it states "Note: This output is for digital channels only."