What a total crock.
Tomlinson Holman is to the present (and prior) decade what Amar Bose was to the 70s and 80s. Its all just a bunch of marketing crapola, with almost no genuine technical merit.
The company that I most associate Tomlinson Holman with today is Audyssey. Now, to be fair upfront, I havent experimented with their ultra-expensive professional grade gear, but Ive plenty enough experience with the stuff that goes into mass-marketed stuff from the likes of Denon and Onkyo to know without a shadow of a doubt that it is crap. And this isnt just my opinion. Many reputable audiophile types have reached the exact same conclusion, and anyone who has any genuine interest in this should have no difficulty finding further corroboration of this.
Except for people who evidently have lost all of their high-frequency hearing, most everyone else has observed the exaggeration of high frequency that you get with Audyssey EQ (and the more recent enhancements, MultiEQ) for example. There is no denying the fact that this occurs, and there is nothing whatsoever musical or technically accurate about it. The ultimate explanation for why it is there is so that in showrooms, the salesperson can demonstrate the effect and it will be clearly audible to the customer that it has an improvement on the sound quality. Secondary to this reason, there is also a technical reason. Instead of striving for a flat on-axis response as it should, it strives for a spectrally flat power response, at least from the midrange on up through the highest frequencies. As anyone who knows anything at all about speakers in rooms knows perfectly well, the higher you go in frequency, the greater the disparity between the on-axis response and the power response, owing to the increasing directivity of the tweeter. As such, if you make the power response flat, the necessary consequence will be a horrendous exaggeration of high frequency in the on-axis response, and this is precisely what Audyssey does.
There is nothing accurate or technically justifiable about it. There can be no question that they are perfectly aware of this, and that they choose to ignore because it is good for business. More recently, they added Dynamic EQ, which is a modern take on the old-fashioned loudness control, that is purported to be technically correct in contrast with those older loudness controls. There is much irony here, because Holman himself was a vocal critic of those old loudness controls, and he more than anyone else is probably the reason that they went away. But they sounded good to most people, and most people who owned receivers and preamps back in the 60s and 70s when those controls were popular miss them greatly. Now, if Dynamic EQ worked, there would be reason to forgive. But Ive tried to use it, as have many others, and the near-ubiquitous assessment is that it is the worst-sounding processing of any sort that anyone has every heard. It adds a sort of rumble that sounds so awful that it defies description and even the imagination. They also added Dynamic Volume, which is dynamic range compression, and it might actually work, except that hardly anyone could say because no one uses it because it order to use it you have to also engage Dynamic EQ.
I have listened to Audysseys MultiEQ extensively and I have taken extensive measurements. The measurements that I took at the main speakers seemed to indicate no significant difference beyond the exaggeration of treble, and did not agree with what I was hearing. I was confused for a while, until I took the subwoofer out of the equation, and then saw a difference in the main speakers, that was applied to the main speakers in the absence of the subwoofer. I put the subwoofer back into the equation and measured the effect there, and it was then that I realized that the predominant effect that I had been hearing, aside from the exaggeration of treble, was an effect applied to the subwoofer. Once I realized that, I focused my effort at manual correction sans Audyssey on the subwoofer. The Onkyo receiver that I was using provided digital equalization of the subwoofer separate from the main speakers, and after a little bit of effort I was able to get the subwoofer to sound excellent using the manual equalization. Then I moved the manual equalization settings for the main speakers to flat, and finally the system sounded the way that it should sound, which is to say, enormously better than it sounded with Audyssey MultiEQ. Now, it may be that the manual equalization capability is made available by way of the Audyssey technology in the receiver, but if so, this is the only part of Audyssey that I found to be the least bit useful. For all the hype, all that there really is in it that is worth a plug nickel is the manual equalization capability for the subwoofer. With a better subwoofer I likely would not need this at all, particularly a subwoofer with a built-in parametric equalizer.
I reassert: Tomlinson Holman is the modern equivalent of Amar Bose.