Sorry if I am wrong, but it sounds like you are saying the center is missing the highs and mids that are present in the towers. If so, have you checked to see if the tweeter in the center speaker is working? If not, cover the center's tweeter with something like a 3X5 card to see if there is a difference in the sound. If no difference, that tweeter is probably blown.
If the monster surge protector is a problem, it should affect all speakers the same.
If the monster surge protector is a problem, it should affect all speakers the same.