Your Pro Monitors and centers are rated to play down to 47hz... I would cross them over at 80hz and start testing FR in your room with test tones and see how the room responds..
If you have any drops in FR around where you crossed them, try a different setting and test again... Let your graphs of your room decide what to do...
Otherwise if you have a laptop you can get
Room EQ Wizard fired up and digitally sweep your room with a mic. This involves some cost, usually around $150.00 in parts..