I recently hired an audio engineer for two days (costs less than high end cable) who had the MLSSA speaker measurement equipment along with all the impulse, spectral decay, modal, FFT, etc analysis equipment. I experimented with speaker placement, room treatments and both the Tact and Sigtech signal processors over those two days. I then listened to both DSP units for a week. Since I have Dunlavy V speakers I have the exact anechoic frequency/time response curves of the actual speakers for comparison to my in room measurements and don’t need to worry that my speakers are not impulse coherent. Using the impulse response measurements it is easy to see the room effects. From FFT you also see the modal response. The secret to good room treatment is to smooth the frequency response while damping the first and most of the second reflections while leaving the direct sound and later reflections to provide air. Sound travels at about 1 foot per millisecond. Reflections under 5-7 ms are perceived as colorations. Over 30 ms the perception is of ambiance, reverberation or echo. The best DSP units use algorithms that are designed with the psychoacoustice s in mind as well as with variable amounts correction with respect to frequency. The best are amazing. I first used the RPG Room Optimizer software to get some ideas of my options for speaker placement and modal analysis. I moved the speakers and listening area around my dedicated room both listening and measuring (modal and impulse) until I got what was the best untreated response and sound. The RPG software (within its level detail) was roughly similar to the actual measurements and I recommend it highly since it recommend where to put the passive treatments. I used the Sigtech with basic ASC/RPG room treatments and without. The Sigtech without any passive treatments corrected (and sounded) significantly better than the basic passive treatments alone, particularly in the 20-80Hz range. Adding, the passive treatments at first reflection points with bass traps and using the Sigtech improved the sound only a little more. The Sigtech provides the most impact on large scale complex orchestral/choral/opera recordings. Especially on those with heavy bass (Mahler, Wagner, Stravinsky) the improvement is amazing. On simpler ensembles like rock and jazz the bass articulation and detail is noticeably improved but not a lot more than with large ASC bass traps and passive treatment. However, my room is pretty good to begin with. The Tact unit based both on measurements and listing is not as good as the Sigtech and I would not recommend it for a two channel very high end system. The Tact unit added noticable digital glare in bypass mode which I did not hear with the Sigtech. It also was not as accurate in its correction as measured by using the MLSSA measurements after using its own measurement/correction software. I think it would be fine for most home theatre applications. I listen primarily complex classical, heavy metal, opera and art techno. I bought the Sigtech and couldn’t live without it. My wife and our two female friends who participated in the evaluation tried to convince Sigtech to leave the loaner unit with us until our unit could be manufactured. Your Mileage May Vary.