Thanks for all of the additional responses. Some additional info...
I accidentally forgot to save the reading the reading that I took before I added any traps. Thus the comparison between 1 trap and 4 traps. To further complicate matters, when I opened my MDAT file today, ALL of the readings were gone except for the last one taken the other day. What the happened?
The SPL difference between readings... glad you brought that up. I am almost sure I was using the exact same Windows volume, REW, and pre-pro volume settings for both readings. I don't understand why the difference. Anyway, I adjusted the volume on my pre-pro to get a reading with peak SPL closer to the initial reading. I hope this is the right way to approach this.
Also, one other error I noticed between my 1 trap reading and my 4 trap reading... the open port on my sub was pointed away from the wall on the former and toward the wall on the later. I did some readings each way, and this definitely seems to make a difference. The new reading below reflects the port pointed away from the wall again.
One more thing about the reading below... I added one more 34" superchunk bass in the middle of the back wall-ceiling corner.
Another question... I tried switching my waterfall from logarithmic to linear. However, it comes out all scrunched up with I do linear (see below). What am I doing wrong here?
In general, I still don't feel as though I hear the tightness I would hope for. If it makes any sense, I kind of feel like it's all or nothing with the bass. It's either not there or it's overpowering everything and lacking in definition.
It sounds like it might be another six months before I get my new dual subs (which will also include EQ options). :-( Until then, I can tinker around with seating and sub location.
I just want to know that the countless hours and money that I sunk into building these bass traps is at least having some positive impact.
Also, DrWho, can you explain how I would measure the frequency response in the corners where I put the acoustic treatment? Do I simply remove the treatment, place the SPL meter in the corner on my tripod, and take a reading?