I've been tweaking my Definition 2 sub EQ for about two months. The EQ is a dbx pro unit, which has self-tuning via pink noise to generate a graphic EQ curve. You have 4 bands of parametric EQ beyond that. There are other setups but this is the one I've been using. This unit has a laptop interface sort of like a TacT unit, though far less sophisticated. Still, for what it is/does it works very well.
I'm running the subs to about 125 hz where the mains start tapering from there in my room but have some output down to 40 hz. I haven't noticed any phase issues in the bass.
Obviously, the potential is tremendous - complete flexibility and honest ability to achieve whatever sound you want in the room. As those experienced with EQ and the like will rue: "Flexibility is the enemy of satisfaction - you always know there's more and will overanalyze." While I've been happy with what I've achieved with an SPL meter, test tones, and paltry understanding of parametric EQ/acoustics, it hasn't been quite "right". Midbass has been plump and low bass not quite as forceful as I'd like.
Well, I sat down with REW this w/e and figgered it out, to a point. There's a ton there I won't ever need, especially since I'm using an external EQ. I was able to get the measurement stuff working though, it's not too hard.
The short story is that in 2 hours, including the upfront learning curve of getting the software operational, I was able to EQ each speaker independently +/- 3 dB from 20 - 200 hz in my room. The target for this exercise was to get "flat". I will likely save this curve in my EQ as a reference and move onto others like TacT does - varying curves for volume levels and/or purpose. Funny, I'm not sure "flat" will be my preference but whenever I need it, it'll be there.
This tool makes quick work of evaluating the working environment and adapting strategies to achieve optimum results. Compared with shooting in the dark it's incredibly effective. Being able to see exactly what's happening and addressing it in a real-time environment is the bees knees - I'm sold.