Home Theater Volume ?

Most action movies are mixed with a huge amount of dynamic range. Big changes are normal.

If you can't hear the dialog at low volumes you have a problem of some sort (speaker placement and acoustics are candidates when the system is properly calibrated) with your setup.

I had to individually adjust my center channel up a few dB's above the rest of the speakers with my H/K receiver. I had a limit of +10dB's and I used all of them. Backed the sides down to about +7dB and now movies sound great.
Combine that with the Dynamic Range compression feature and you should be good to go.
The problem was only in Dolby Digital.

Correct me if I'm wrong here:
Setting all of the gains up so high is like using an equalizer with all the frequencies boosted to give extra gain. I was always taught to try to stay around 0 gain to keep the truest/cleanest signal.
From what I was taught, I would have the sides at about-1db and the center at +2. You may have to use more volume that way to get the same decible level but you will be using the amplifier to get the increased volume instead of circuitry to get the added gain. Just my 2 cents.......I'd love to hear some feedback here!

Elevick is right, keep it as close to 0 gain(or flat) as possible. Remember that for every 2dBs that you increase, your amp has to work twice as hard(or something along those lines).

Power doubles for every 3dB, although assuming you don't exceed the speaker's power handling (not likely) and don't have audible distortion it's not an issue.