Great, glad you found the problem. I have always thought that the as-calibrated center channel level was low, and have always bumped it few db on every receiver I have owned, even back when I had to set it manually with a sound level meter.
I have an old set of NHT's. SuperOne bookshelf for the center on a shelf above the TV and SuperTwo towers for the left and right speakers. They are not terribly efficient speakers, they are rated at 86 or 87db efficiency, most newer speakers are rated at 90+db so I do have to turn up the volume a bit on them but they very accurate and sound really good. Don't think I would replace them unless I had to, for the quality of sound they were an unbelievable deal.