Hmmm. I just looked in the Yamaha manual and there does seem to be some kind of Center Graphic Equalizer. Here is what it says "Use this feature to adjust the built in 5 band equalizer so that the center speaker tonal quality matches that of the left and right main speakers. You can select the 100Hz, 300Hz, 1kHz, 3kHz, or 10kHz frequencies". It seems to be set at the default setting (all flat). I will play around with this and see if it makes a difference. Thanks!