Since you like JJ's work, you may be interested in the history of it. I think it was 1999 when I saw a review of Tact Processor/EQ in an audio magazine (stereophile?) where it received a rating of 10 out of 10 in sound quality. So I proceeded to order one at a cost of $10,000. I sat through the onerous interface of TacT and activated it once all the filters were programmed. I was shocked at how seemingly the walls of my small theater had collapsed -- just like the review said. For the first time, I had correct blending of my sub and the rest of the speakers (powered/active Paradigms).I have a lot of respect for JJ Johnston and feel his presentation on the Acoustic and Psychoacoustic Issues in Room Correction that can be downloaded from here: http://www.aes-media.org/sections/pnw/pnwrecaps/2008/jj_jan08/ represents the state of the art understanding of room correction.
Then I did another experiment. I hooked it up on the output of my PC on the way to cheap powered stereo speakers for my computer. You know, the plastic little cups they call speakers and crappy box they call subwoofer. I was shocked and amazed and the difference it made there. This beyond cheap system had superb imagine and again, smooth bass response.
I set up meeting for my signal processing group and repeated the demo for them with PC speakers. Everyone was shocked at the difference it made. So I said let's put this in the audio pipeline of Windows. Resources being what they were, this sat there until we got lucky and AT&T blew up a music delivery system they had. And with it JJ became available. A number of companies went after him but we were lucky to persuade him to join us as our audio architect. We put revamping of the Windows XP pipeline and addition of room EQ on JJ's plate.
During the process, JJ was worried about the CPU requirements of an EQ. He explained that if we just matched the gain and delay between loudspeakers we would get most of the benefits. As much as I was sympathetic to that, I insisted that we get a proper EQ in there. Courtesy of our top of our optimization team members like Serge in that article, the final system barely used any CPU.
Alas, my team was responsible for the audio pipeline. The rest of the Windows including the explorer/shell was in another group. So the only way we could expose the interface was through crude Properties control panel. In other words, very difficult for anyone to discover. And easy for it to get lost as it did in the follow on releases when I, JJ and others left Microsoft.
Sadly Vista took so long to release that by the time it came out, consumer level Room Eq was available and hence we lost the opportunity to really showcase the power of PC to perform such optimizations.