If you are running your speakers as Small, then the crossover setting you chose in the 990 is the crossover used for your subwoofer. I'm assuming of course you are using the 2 subwoofer output jacks on the 990 to feed those 2 channels on your 7700. The highest crossover setting to the sub is only for that particular speaker(center). The other speakers bass information will crossover to the sub at the crossover you chose for them. This is the advantage of having quad crossover settings.