Toole and why I like Tone Controls

erik, I am certainly not the one to argue as I use the best tone controls ever made, full spectrum room control. I can adjust the frequency response any way I want and see the actual results on the computer that controls the system by impulse test. It gets even better. I have dynamic loudness compensation. The system will follow the appropriate loudness curve depending on the actual volume so no matter what the volume the music sounds exactly the same. Various curves are stored in memory to cover specific problems. As an example I have a curve with a notch filter centered on 3000 Hz. I use it for sibilant voices and such. The unit is a Tact 2.2X. Tact went out of business. Trinnov and Anthem make units that are good but do not quite make it to the level of the TACT. I could never live without it. Fortunately the Tact is very well made but if it died I would probably go with the Trinnnov Amethyst.    

Tim, it would be nice but doing it requires complicated programming of several DSPs running in concert and in control of the entire frequency range at 1/2 Hz intervals in a 48 bit system. You need to have the native frequency response of the system to start which means you have to do impulse testing with a microphone. Then you create filters that make the system's frequency response perfectly flat and this is the canvas you work from now overlying the inverse of the Fletcher - Munson curves and programming the computer to hop from one to the other at the right volume. 
Now if the front end of the Class D amp were digital the appropriate electronics could be added. I think the company that is most likely to do this at a reasonable price would be Anthem. They have room control built in to some of their units so the basic computing power may be there.
Trinnov has it all except the programming for Dynamic Loudness. You can link your PC to the Trinnov and program target curves into memory so you could create inverse F-M curves and switch to them manually but the programming to do it automatically is not there yet.
Erik, yes, just way more sophisticated. You have to see the computer programming in action. The problem with the Tact system is that it is complicated and consumers had a lot of trouble using it correctly. Tact decided to go direct marketing which was a big mistake. They did not have a trained dealer network to help them out and eventually it all just crashed. The current crop of manufacturers learned from this and have simplified their systems but they also removed a lot of the functionality that made the Tact system so effective like the dynamic loudness and the most amazing bass management which has yet to be matched by anything I have seen. I can change high and low pass filters independently 1 Hz at a time and choose any slope for either filter independently from 6 dB to 80 dB per octave. I can do all this on the fly with my laptop on my lap. The computer also has total control over time and phasing between all the individual drivers and sets the delays automatically when the system is impulse tested. The improvement in sound quality is such that I now digitize my phono amp through a Benchmark ADC. May sound like heresy but there is no turning back. 

Not so audiophilenm, at least in the digital world. I was just like you until about 2000. I just played the music at whatever volume it sounded best but there are several factors that even the smartest audio person can not control for. If I measure any system, even set up by a master the frequency response measurements will look like the rocky mountains. The usual response is, "I didn't know it was that bad." Second, the two channels are never identical. I have seen them vary as much as 10 dB in spots. You can't know how this screws up your imaging until you hear a corrected system. Third is you have no way of managing you individual speakers in time. The sound from various divers is getting to you at different times at different phase angles. This is most critical for subwoofers but also can greatly effect imaging. I have never corrected someone's system (and these are died in the wool audiophiles) and had them think it made their systems sound worse. Their usual response is "I did not know it was that bad." So, until you have measured your own system and had a look at what it is doing then corrected it both in the time and frequency realms, you have no idea what your system can sound like. You are determining what the prevailing winds are by licking your finger and sticking it up in the air. 

I only switch to a different curves for recordings with problems. This is usually for cutting female voices or strings. I'll switch to the curve with the 3K notch filter which smooths things out nicely. Other wise I only get into it when there is a significant change in the system like new amps or re- positioning the speakers or a change in the room like a new sofa. Otherwise it is set it and forget it. 
It would be the rare, truly exceptional system and room that would not benefit from correction not to mention other things you can do in the digital domain like subwoofer cross overs and dynamic loudness compensation. 

A best of the Sex Pistols? They only had one album!