I JUST PUT 2 12" WOOFERS AND AN AMP TO MY MONSOON SYSTEM IN MY 2000 Z28. I NEED TO KNOW IF THERE IS ANY WAY TO MAKE THE PILAR SPEAKERS ABOVE THE REAR SEATS PLAY MUSIC INSTEAD OF JUST BASS? I DON'T WANT TO ADD ANOTHER AMP OR CHANGE THE HEAD UNIT. ANY HELP WOULD BE APPRECIATED.