Every receiver has a way to turn off certain channels, sometimes automatically if not detected through self-calibration. However, if you're looking to re-direct the sound from speakers 6/7 into a centralized 6th speaker I'm not sure it can do that. I know if the central speaker is missing, then dialogue will get redirected to L/R, but not sure sure if surround sound works the same. You may need to pair down to 5.1 to maintain symmetry in your surrounds.