I'm going to share something else I learned last night.
Here is what I was able to obtain by moving both of my subs slightly, moving my seat up about a foot to get out of some nulls, adjusting the sub distance in my AVR, and using the PEQ to bring down a 15db mountain at 58Hz.
Nearly ruler flat 15-80Hz with zero
smoothing. Also there are no
bass traps or absorbers of any kind in this (live) living room except for carpet and furniture. A true testament to dual subs and proper setup.
However, I didn't like how it sounded. It turns out that I really like 60Hz, and flattening that peak left me unsatisfied with the loss of impact. It seems that notes in the 50-60hz range give a visceral feel in my room, and vibrate the floor under my seat. I wanted that back, so I dialed the PEQ back quite a bit so that it's now a 6db peak rather than completely smooth. It was previously a 15db mountain. So the lesson I learned is that I don't like a flat bass response.
Some songs that I use for testing:
Transformers 2 - The Fallen
Transformers 3 - Lost Signal
Mass Effect 3 - Reaper Chase
There are some very tight, hard hitting bass notes in these songs that use 50-60Hz notes to create impact, and it's addicting. I didn't know what I had until I lost it!
I also am using Dynamic EQ to lift the bass region and create the downward slope that is favored by many.