I figured I'd post a brief update about the Rane EQ that I ended up purchasing. First, I ended up with a damaged unit on the first time around, but the seller replaced it and all is well at this point. The unit is fully analog, so the adjustments all take place via dials which makes precision a little difficult, but with patience it works quite well. To make adjustments, I eliminated the room effects by looping the output of the unit back into the mic input of my extreranl soundcard. I used this method to set each filter to the precise frequency needed. After that I adjusted bandwidth and cut/boost according to the dials and did some measuring, followed by fine tuning. I was able to produce a much better frequency response below 80Hz.
I did run into one problem, which has nothing to do with the EQ or the sub. I was not able to eliminate my peak (fully) that occurs around 63Hz. Turns out this is caused by my SongTowers, despite the fact that they are crossed over at 80Hz. I still need to reduce this peak by about 5dbs, but am at a loss as to what, if anything, I can do. I measured around my listening position, and also moved my STs within the limits I have and the peak remains. Any ideas for a solution? Large bass traps are not an option either. Also, I'm not sure if running an EQ on the mains is a good idea. I wish the crossover was steeper, as that might have been enough to further reduce the peak as the STs roll off to the sub. I may just have to live with it for now.
Otherwise, I find that the sound is definitely improved in the lower frequencies. Overall, the bass is a little less boomy and doesn't appear to overtake/drown out upper frequencies as much as before. Hard to explain really, but I like the changes as opposed to leaving the signal untreated. And this EQ adds zero perceived noise to the signal and no issues with buzz/hum either.