PCchips M586MR Manual page 46

4: Software & Applications
avoid hardware conflicts, DO NOT enable this option when the
Line-in/Rear jack is connected with a line-in device. While the 4
speakers mode is enabled, turn on/off the output of the front
speakers and adjust the volume of the speakers so that the
front/rear speakers have the same volume.
Demo
Execute the "Helicopter" demo in the C3D HRTF Positional Audio
Demos of the PCI Audio Application. When you hear the
helicopter flying behind you, it means that the rear speakers are
working properly.
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