Rumbler

I'm so happy to find that the headrest speakers work. System is stock radio. fader fades from front speakers to headrests, and there is bass coming from the little rear speakers. Had to clean the gunk off the volume controls to find that they actually work. On my vehicle the surround light is lit red and there is no power light. Depressing either button has no effect that I can tell. Surround light stays lit at all times My question, what is the function of the power and surround buttons?