Personally I would consider dialing the subwoofers built in Xover as far up 'out of the way' as possible and use the adjustable crossover on the 950 as a first configuration. If you move the built in sub xover high enough (most will go up to 120-200 Hz) it shouldn't interfere with the pre/pro xover. Set your speakers to 'small' and cross over at 40 Hz in the 950.

See if that works for you.