What's the crossover point when the fronts are large and the sub is set to L/R + sub?

I received my 990 yesterday and found the setup pretty straightforward. The sound is great, and I'm eager to do some critical listening in the next few weeks to tweak everything.

My setup includes Paradigm reference studio 40s up front, the matching center, a paradigm 2100 sub, and a couple of older floor-standing Cerwin Vegas doing surround duty. I first set it up manually with the fronts and surrounds crossing over at 40, and the center at 60. Running the auto setup yielded the same settings (or did I do something wrong?), plus did the delays quite well. I'm curious, though, about setting the fronts to large, and having the sub pickup some bass from them, but the manual doesn't specify the crossover at which the fronts' bass is fed to the sub at that setting. (That is, the fronts get full range, and the sub gets 80 and below, duplicating everything up to 80). I'm guessing it's around 80, but does anyone know? Also, does this setting only feed from the fronts, or also the surrounds? The manual speaks to this setting only with regard to the setting for the fronts, but I wonder....

Thanks,

Mark