I mentioned in a previous thread that there a few things in the video that did seem right to me. One of the biggest for me was the description of the Harman Target Curve and it being the only curve anyone would need. I'll attach some words from Floyd Toole that appear in the same publication the graph of curves come from. The whole paper is free and worth reading if not already. The Measurement and Calibration of Sound Reproducing Systems.
https://www.aes.org/tmpFiles/elib/20220817/17839.pdf
"Research by Olive et al. [48] was distinctive in that the loudspeaker used was anechoically characterized, the room described [49], and high-resolution room curves measured. In the double-blind tests, listeners made bass and treble balance adjustments to a loudspeaker that had been equalized to a flat smooth steady-state room curve. The loudspeaker had previously received high ratings in independent double blind comparison tests, without equalization. Three tests were done, with the bass or treble adjusted separately with the other parameter randomly fixed, and a test in which both controls were available, starting from random settings. It was a classic method-of-adjustment experiment. For each program selection, listeners made adjustments to yield the most preferred result. In Fig. 14 the author has modified the original data to separately show the result of evaluations by trained and untrained listeners. This is compared to the small room prediction from Fig. 13(a). The “all listeners” average curve is close to the predicted target, except at low frequencies where it is apparent that the strongly expressed preferences of inexperienced listeners significantly elevated the average curve. In fact, the target variations at both ends of the spectrum are substantial, with untrained listeners simply choosing “more of everything.” An unanswered question is whether this was related to overall loudness—more research is needed. However, most of us have seen evidence of such more-bass, more-treble listener preferences in the “as found” tone control settings in numerous rental and loaner cars. More data would be enlightening, but this amount is sufficient to indicate that a single target curve is not likely to satisfy all listeners. Add to this the program variations created by the “circle of confusion” and there is a strong argument for incorporating easily accessible bass and treble tone controls in playback equipment. The first task for such controls would be to allow users to optimize the spectral balance of their loudspeakers in their rooms, and, on an ongoing basis, to compensate for spectral imbalances as they appear in movies and music."
There is also a slide from one of Sean Olive's documents that shows some more information
https://www.juloaudio.sk/Umiestnenie_reprosustav/History of Harman Target Curve.pdf
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So while there is a lot of similarity in preferred room curves the idea that you can pick one and apply to all speakers with all directivities in all rooms and have them sound the same or right is not a good one.
In my own correction routine I have moved away from having DRC use a target curve to define the overall steady state response. While I have had good results using that method it can be quite time consuming and complicated making different target curves trying to find improvements.
What I do now is use DRC to correct to a flat response and then apply a layer of PEQ over the top to set the tonal balance which was judged by ear. This PEQ is a collection of shelving filters spaced an octave apart which allows the slope to be changed consistently or varied at certain points based on how it sounds. Each speaker and room would be different and this sort o approach allows easy modification of the tonal balance while listening in a controlled way. Sometimes a small change to the Q of the shelf or gain by a a small amount can impact the perception quite a lot. Eventually things start to sound more "right" for want of a better word.
Experimentation in this sort of processing is important because there is still a fair bit of alchemy in getting the best result as the method itself is impacting so many different factors at once. The usual factors pointed out as to why "room correction" is not a good idea are valid in of themselves but in my own experience if they are considered and managed then it is still possible to get a really result but one with a one size fits all curve.