"The room can totally wreck, or make, a system"

40 hz null pretty tough to deal with

90 hz peak, I would look into a trap(s) tuned for 90 hz

Peaks are far worse to listen to than nulls and often easier to fix.

Room treatment is my second most expensive component. 

Room treatments can only get you so far.  In my experience, DSP-based room correction was needed to bring audio bliss to my systems.  My hunch is that pending money on DSP is likely going to by more cost effective than room treatments as a primary solution.

@fynnegan  I had a similar issue 50hz to 100hz…Applied room treatment, bass traps & absorption panels, only thing that corrected the problem was changing out my speakers to a set of Soundfield Audio MMW-1’s Cardioid Stand mounts with built in active front & Top Firing Subs controlled with DSP. If you don’t know what a Cardioid Speaker is Google it, it’ll certainly apply to your situation.  I opted to have my set built with Beryllium Tweeters and I have to tell you, In the past 5 years I’ve gone through 11 sets of speakers going nuts trying to correct the freq bump in the room. These are number 12 and they’re absolutely amazing and in combination with my room treatments the bass issue has totally been corrected and am finally off the speaker merry go round and finally enjoying my music!

I just got back from the Florida Hifi Expo in Tampa, I gotta tell ya, I seriously felt my set up sounded as good if not better than many of the High End systems I saw. I went specifically to stop by the Soundfield Audio’s room just to thank AJ, the owner of Soundfield Audio, for finally getting my room sounding right… and here’s the kicker, No Lie… His room was prob one of the best sounding rooms at the show and when I told him that he said he’s been hearing that all day. 
So yes DSP at this point may be your only option as it was for me and combine that with a quality speaker custom made for your tastes and room’s needs and I can assure you,  you’ll never look back ! 

My room had a bunch of openings and a fireplace. It is carpeted, with six absorption panels and one of those bamboo folding room dividers with a heavy comforter hanging over it on the right side where there is no wall. The fireplace glass is covered and one of those absorption panels is in the first reflection point on the left wall.  I bought a couple of 18”, triangle bass traps that are in the top front corners. I also have a couple of large pieces of hard foam board that I occasionally move around to see if I can hear any difference.

With all the openings, a wife and two dogs,  I think I have done about all I can do to the room and I am really happy with the results. Even with the dogs sleeping and snoring on either side of me. 🐾🐾