Need a bit of clarification. I have "small" speakers for my side surrounds but large speakers for my rear surrounds. My question is if I select small for the sides (causing the rears to be set to small) what difference does it make if I set the x-over point for the rears to 60hz. The larger question is, I guess, what does the processor do differently to the signal when small is selected instead of large?

When speakers are set to "small" the processor engages bass management based on the associated crossover point you've picked. When they are set to large, the full range signal goes to the speakers.

Even if you are using speakers that really are "large" from a bass management perspective (a -3dB point of somewhere in the 20Hz to 30Hz range), I don't see a compelling reason to use them that way. There's just not enough content going to the surrounds that reaches that low. I'd take the rear speakers' -3dB point, double it, and set the crossover to the nearest setting to that number.

Thanks Gonk. I can now sleep again.