Have you tried sticking your ear up to the VP100 and checking that all 3 drivers are working?
I have the VP100 with M80s, and it works fine. From the sound of it, your setup is working fine except from DVD. Is that correct? (for example, using Dolby Pro Logic II or DTS:Neo6 with a CD or TV signal).
Center crossover on my VP100 is at 100Hz, but I don't know if you have the option of different crossovers for different channels. Even so, the crossover shouldn't make the difference on how loud the center is compared to the other channels. It might make a difference in how it sounds, but not in how loud it is.
