I have a Theta CBIV with Dirac playing multichannel audio in a well treated room. The improvement is palpable in all the ways you might imagine. I have a cleaner, more fully integrated soundstage. As a bonus, I stopped fussing about getting speaker and sofa positions just right and let Dirac do the work. A few notes: some people report problems using the "chair" setting rather than the "sofa" setting. That said, Dirac cannot optimize across the entire sofa. Lastly, when you set things up make sure you move the microphone in three dimensions -- left/right, up/down, and forward/back, not just the first two that you might see on your monitor. (There is a way to change the picture as you are setting up Dirac to see the third dimension.) I failed to do this the first time I set it up and was a bit underwhelmed by the filter. But once I got it right...wow!