Wow, I recently was wondering the same thing, so I spent the better part of a day listening to a few tracks over and over with different settings for small/large (all my speakers are big), X-over on receiver, X-over on sub, sub level, etc., and made a noticeable improvement in the configuration.
At the end of it all the X-over on the receiver is set to 80Hz, and all the speakers are set to small.