Of course, it's good when we don't have to correct rooms electrically but can do it passively--this can be almost impossible in the bass region. I'm not at all surprised as to your findings--I only wish you had found our company first. We are an acoustical engineering company that designs listening rooms, but recognized this issue and we were not satisified with any of the devices on the market. We make a PARC device designed specifically to deal with the bass mode problems. When we designed it I was very concerned about signal purity and having a degree and graduate work in digital signal processing I knew that I wanted to stay in the analog domain. Part of this was due to my love for vinyl and upcoming formats that might be degraded in the digital domain, but part of it was just a characteristic nature of running the signal back through an A/D and D/A converter. So we designed a 3 band parametric notch filter system that has a range of 16 to 350 Hz, Q factors of 1 to 11, and attenuation up to 18 db. I don't think any other unit has anywhere close to that head room. It's digitally controlled but the audio signal remains solely in the analog domain. The unit is calibrated using proprietary software that has a psycho acoustical response filter (it reacts similarly to the human ear in terms of gating times at different frequencies.) You can also calibrate the unit in a manual method with test tones, but this is more time consuming and not as accurate. It also doesn't have the advantage of being able to see the graphed results in near real time.
The other thing that is very interesting is that you have Talon speakers. We used the PARC at CES on a pair of Talon's new Firebird speakers. Mike Farnsworth, president of Talon, was delighted with the sound and told me he wants the PARC at all shows. He had not been happy with any other correction system he had tried in the past. We will be with Talon again at HE 2003. For more info on the PARC.
Obviously, I'm clearly biased here. I do believe we designed an incredible product that sounds better than anything else that corrects for room modes, with excellent build quality using connectors like WBT and Neutrik. But perhaps more impressive was making this device at a more affordable level.