Gigabyte GA-6VM7-4E User Manual page 49

Four Speaker & SPDIF Introduction
e. Click "Digital" item, Line Out will be change to SPDIF Out.
f. Recommend you to select "Autosense", It will automatically detect the type (mono or stereo)
of the audio connector that you plug into Line Out audio jack, then configure Line Out to
either SPDIF or Speaker accordingly.
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