Well, there's no magic answer. The first question is whether or not you have calibrated your system with a sound level meter and a test disc like Avia. All of the speakers, including the subwoofer, should be outputting the same sound level.
I find it strange that your center is set to 10, and all others to 7. In my system (HK AVR520, M22, VP150, QS8 and SVS sub), the center channel has always been calibrated a couple of db lower than the fronts. Again, I have calibrated all speakers with a sound level meter and Avia, and the center is set lower to match the mains. From there, I might bump it up one db higher to increase dialogue.
There's also no real reason to have the levels set up so high. You can do the same matching by starting at 0 in your HK setup, and then moving a couple of db up or down. This will give you more leeway and will be easier to work with.
Finally, I think you need to raise the crossover settings in the HK. Keep the speakers set to "small", but 60Hz is too low for that system. You can do it simple, by setting everything to 80Hz, or you can set the fronts to 80Hz, and then the center and surrounds to 100Hz. This should give you a more balanced system, and give you more low end by sending more bass to the sub, which will handle it better than the other speakers.
There are other issues such as placement, but I won't get into that. Good luck.
