2005 GMC Safari Owner's Manual - Page 159

Rear Seat Audio (RSA) This feature allows rear seat passengers to listen to any of the sources: radio and CDs. However, the rear seat passengers can only control the sources that the front seat passengers are not listening to. For example, rear seat passengers may listen to and control a CD through headphones while the driver listens to the radio through the front speakers. The rear seat passengers have control of the volume for each set of headphones. The front seat audio controls always have priority over the RSA controls. If the front seat passengers switch the source for the main radio to a remote source, the RSA will not be able to control the remote source. You can operate the RSA when the main radio is off. PWR (Power): Press this button to turn the system on or off. The rear speakers will be muted when the power is turned on. VOL (Volume): Press this knob lightly so it extends. Turn the knob to increase or to decrease the volume. Push the knob back into it's stored position when you are not using it. The upper knob controls the upper headphones and the lower knob controls the lower headphones. 3-49