What kind of "profound practical verification" are you looking for?
Profound is what makes sense to my ears. That is undoubtably the best instrument I have to evaluate distortion. With that I can verify whether or not the response you measured is valid for me or not.
I just listened to some series of white noise and tried to pin point any resonances in the higher spectrum. Without further ado, here is what I ended up with:
Peak 5 kHz, -3 dB, Q = 6
Peak 7 kHz , -6 dB, Q = 8.5
Peak 9 kHz, -2.5 dB, Q = 9
Peak 12,8 kHz, -3 dB, Q = 6
Shelf: 10,5 kHz, -2 dB, Q = 1
Some comments on this:
- The 7 kHz peak was by far the most prominent resonance. That is the exact opposite of your measurement which shows a trough at that frequency.
- The even order stepping of 5, 7 and 9 kHz does indeed imply a driver related resonance. In my case it peaks with roughly the same amplitude (compared to my hearing) but with the fundamental at 7 kHz instead of 5.3 kHz. Maybe that shift is caused by a smaller volume in my ear compared to that of the GRAS fixture (which simulates a rather long canal, including the resonator's cavity).
- Variations of the seating position (this one was subjectively centered) did a lot to the treble response. Pulling the can a little bit backwards makes the sound much brighter at the top end.
Continuing with a music test I found that the settings above make the response less harsh but also a bit dull. I would say it is a matter of taste and depends on the genre / mix of the album. The first album I listened to when I bought the X2HR is "Parcels - Vol. 1". Stell a perfect fit today. There is just the right amount of sparkle, neither too dull nor too sibilant. It also performs quite well on my Jazz playlist. However, for an everyday use case with a wider mix of albums the "tamed" response is obviously less critical. Also, I noticed that the response without EQ works better at lower volumes while the response with EQ works better at higher volumes.
I also listened to your presets provided in the first post. Again, only treble for this case.
Unfortunately, the noise test reveals a lot uncontrolled hiss versus my own preset. Then music listening. For tracks with a lot of HF content the compensated curve is obviously better than nothing. As for your versus my curve, it depends on the mix, once again. Overall I would say that my own preset sounds flatter, more balanced, but also less vivid. The 43AG preset has a little bit more attack and can make the treble shine a bit more in certain areas. On the other hand, it gets a bit sharp from time to time.
To sum up:
Does the high-frequency EQ deduced from your measurements fit my hearing? No.
Does the pattern of the resonances show general similarities? Yes.
Would the look at the measurements alone capture the whole story I would perceive in real life? No.
Does the listening test finally help to prove or disprove the resonances in your measurements as much as the EQ deduced from that? Yes.