The PCM light on the front of the receiver lights up when the Yamaha unit is receiving a PCM signal from a source such as a DVD player. Standard PCM signals are 2-channel digital signals. Since the
Yamaha receiver is just displaying what type of signal it is receiving, there are no settings on the Yamaha receiver that would force it to say Dolby Digital. If you are watching DVD movie and the
PCM light is lit, verify the digital audio out settings on the DVD player menu to make sure that both Dolby Digital and DTS are enabled.
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