ProScan PS3109YX1CH2 User Manual page 37

AUDIO OUTPUT Provides variable-controlled or fixed-level stereo
audio output.
Variable output is ideal when connecting the TV to an amplifier
that does not have its own volume control or remote control.
Fixed output is ideal when connecting to an A/V receiver or
amplifier that has its own remote control.
You can choose the type of audio output by selecting the Audio
Output & Speakers control panel in the Audio menu.
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