Actually, supposedly it is recommended that for the best flat response and mix of speakers and sub, you should choose a crossover at approx twice your spec'd low freq response of your speakers. For me, my speakers are spec'd at 24Hz but I've found that my ideal crossover is around 40 Hz. As you mentioned, if your amplification is not stout enough to drive those 10" drivers in your speakers to low Hzs and high SPLs, then you may be better with an even higher crossover if your subwoofer is driven more stoutly.

I love the 950s triple crossover for movie viewing... my 950 yearning is for a straight wire 5.1 and 2.0 analog bypass without any bass processing at all if switched off. Ideally, that's what the 950 (and 1066) should do.