In this day and age of 5.1 channel surround sound hype, an amazingly basic fact has been ignored: most consumers listen only in stereo or mono. This is due to the fact that television channels are delivered via several means including terrestrial, cable and satellite. While receivers for these services always include some sort of digital output to deliver the Dolby Digital (AC-3) signal to an external A/V receiver, they also include more common connections.
Most all set top boxes include the standard red and white pin-jack (aka "RCA") connectors for delivering analog left and right audio signals. Connect these plus the yellow connector (or the S-video connector if present) to any modern television set, and reasonably good sound and picture will appear. It will be limited to stereo audio and standard definition video, but it works.
A far worse situation can occur if the simplest interconnection is used: the RF modulated output. The seemingly ubiquitous channel 3/4 signal where mono audio and video are delivered by a single cable to the television which is set to (you guessed it) channel 3 or channel 4. In some cases, such as with very old television sets, this method might be the only choice. Unfortunately it seems that it is sometimes used by installers as a quick way to get the install done even when alternate high-quality approaches exist, much to the detriment of the sound and picture.
Beware when troubleshooting a viewer complaint. Always make sure to ask how they are hearing and seeing the broadcast as the solutions will be dramatically different depending on the method of connection.
