Since I moved into my condo, I have not had a Sub. I sold my Servo 15 when i moved. I figured that in a condo there was no room for it. But I got a good deal on a small PSW250 sub. I figured if it was too loud, no real loss. Well here is what my question is. I have the speaker settings on my pre amp as follows:
Front-Large
Rear-Small
Center-Large
Subwoofer-Yes

I turned my fronts and center to "small" to maybe get more bass directed to the sub. So where should I set the sub's crossover to???? Should it be set higher or lower(numerically) to get the max bass from it??

It depends on where your receiver is cutting off the frequency. Does your manual tell you?

Best thing to do is just try different settings on the sub using different source material(movies, music, etc) and find what sounds best to you.

what palebluedot said is true.

A good rule of thumb setting, though, is 80 Hz. Typically, bass is fairly omnidirectional below 80 Hz, so you won't be able to localize your sub if you use this setting. Just make sure to find out whether your pre/pro has internal crossovers. If it does, you do not want to use both it and the sub's crossover. You will be cutting out too much of the information within the crossover slope, leaving you with a gap in your system's frequency response.

One thing you can do to boost perceived bass output is play around with the positioning of your sub. Typically, placement in a corner of your room will accentuate the output, while moving it to the center of a wall will make it quieter.