low volume center channel ?

[Godzilla71]

Hey everyone,
I was wondering what I could do to improve a low sounding center speaker. At the moment I have the Onkyo ht-s5100 htib. I used the Audyssey 2EQ for the set up and it set the center to -3db I just find in alot of movies the dialog seems really low be it a blu or reg. dvd. some are fine but most seem a bit low. All the other action and sound from the L & R and rears are fine though. I have done temp ajustments on the center raising it +3 or so and that helps a bit. I was just wondering is this just a normal thing depending on how the tracks are put on the disc? or is it have to do with my system not properly adjusted or calibrated.

couple of other quick questions. If I was to slowly upgrade from the htib that I have would it be better to save and get the onkyo 606 receiver and use the exsisting speakers for now or slowly get better speakers first? I assume since the speakers now are 8ohms it would be able to handle different set of speakers if I did that. I live in a apartment so that is why I opted first for the htib that I have. so I really do not know if I would fully be able to enjoy a more powerful set up to it's full capacity. just a thought.

thanks!