Newbie here. I have a basic 5 speaker surround sound set up. Panasonic SA-XR55 Receiver. My question is on the speaker settings, particularly the center speaker where the movie dialogue comes from. Most of the time, the voices are too quiet, or sound muffled. Turning up the volume is not an option, because the rest of the movie gets too loud. So what do i need to do? Adjust? on that center speaker? and how? Thanks.