I moved the sub to the side of the room and was able to get rid of the really big dip. Currently I have the amp gain at about +16db. The mic2200 has a -15db notch type filter just below 40hz on one channel. The other channel has a -10db mid Q filter at about 55hz. It is not quite as smooth as before but I was able to get rid of huge gap.
As I was playing with this tweaking tonight... for about an hour I was trying to boost out of the low spots without clipping the mic2200. Then I thought I would try boosting the amp overall and using cut on the opposite sides of the gap. It turned out well and I was able to get a satisfactory result. Unfortunately it is late, the neighbors in the apartment below me have to sleep and I will not be able to crank up the volume tonight.
It was a lot of work to get the sub to where it is now. Part of me wants to move it back and try the same strategy of boosting the amp and using cut on either side of the low spot.
Thanks for the comments, everyone has been very helpful.