NEC VERSA DOCK Manual page 80

Dock Settings Dialog Box
5. Change the Output Audio To button from "Notebook Speakers" to
"Docking Station Speakers."
This resets the default speakers to the NEC Versa Dock optional external
speakers. When you undock the system, your NEC Versa speakers will
be functional. When you dock again, the external speakers will be
functional.
The volume control knob on the system controls NEC Versa speaker
volume. The volume control knob on the NEC Versa Dock controls the
volume of external speakers connected to the NEC Versa Dock.
4-34 Installing Options and Connecting Devices