[Sonnie]

I believe you are on the right track.

I would probably increase my measurement volume up so that my response line is higher up on the graph. IOW's try to get that dip between 40-50hz to where it will be at 80hz after you have ran your mesurement sweep. That would be about 8db louder. Then move your target line with the house curve loaded to 80db and bring everything else down to there. You'll have a little hump below 20hz... but it may sound pretty good. Or you could widen the bw on the filter at 23hz and bring some of that below 20hz down, if you wanted to.

It also want hurt to boost part of an area that was cut. You are ultimately not boosting your response in this case... only fine tuning the cut.