As an aside, I do tend to purposely use subpar recordings to subjectively test headphones. There is a good reason for this which I will explain in a bit.

This of course comes down to the matter of neutrality. There has been a lot of misunderstanding of neutrality. One such misunderstanding has been the straw-man (falsely assumed of neutrality proponents) argument from none other than Steve Guttenberg that neutrality is an attempt to get closer to the artists' vision. (When I play bass guitar and piano, I could give a rats ass about how it sounds on the HiFi - it's the performance that matters.)

Neutrality is very simple. It's simply a reference, albeit difficult to exactly define subjectively with 100% accuracy, which one tries to shoot for. Subjective impressions of neutrality will vary slightly from audiophile to audiophile. Subjective impressions of what is neutral vary little among recording engineers. (UE was not kidding, making stuff up, or fucking around when they said their reference monitors were tuned by sound engineers at Capitol Records.)

Even though the fuzzy "neutrality" bullseye may be fuzzy subjectively, at least we know there are people who try to shoot for it. Because of personal tastes of sound engineers (or even directives from Studio Execs), we will see variances in how material is mixed and mastered in terms of tonal response. For example, the guy (don't remember his name) who does a lot of the Patricia Barber stuff  prefers a darker sound (with close mic'ing) vs. the guy who did the Bowie Let's Dance remaster a few years ago. Natalie Merchant's Tigerlily is dark compared to the MFSL Pixies stuff.

So there's always going to be variance. What I love about "neutrality" is that this variance will almost always sound acceptable on a neutral system. I like to use MFSL Nirvana Lithium to test upper midrange issues. A few tracks from Radiohead The Bends I also like to use for this test. The K550, at least the pairs which I've heard, massively failed this test. You can call it shitty music or whatever, but the fact it, I feel the interpretations are spot on from the recording engineers for these two discs. Certainly things are supposed to sound aggressive. But on bad system or system with upper midrange issues, this is going to sound nasty.

I like to use Natalie Merchant's Tigerlily to make sure systems are not too dark. Systems which are too dark tend to suck the life out of that record. I also use Talking Heads Naive Melody to test for a variety of many things (too much bass, vocal sibilance, percussion nasties, etc.)

What I don't use is classical music. Classical music is generally bandwidth limited. Now comes the question: is a transducer which sounds good on classical / girl+guitar / flamenco guitar, but not with pop a good transducer? IMO, the answer is an unequivocal no. I'm not into mid-fi. What is comes down to is that a neutral system will be the most flexible with the most recordings for most (but not all) people.

Does this invalidate personal preferences? The answer is also an unequivocal no. Heck, I happen to think the HD800 works really swell with Tigerlily. The HD800 really helps liven up that recording. Although I'm sure others prefer Tigerlily from the LCD2 instead.

BTW, I do prefer a very slightly dark sound. The Paradox s/n 001 fits the bill. So do my modded Jades. The UERM is slightly too "reference monitor" for me.

Finally, generally as along as a transducer has smooth response, I'm OK with it and can adjust. So even then, I wouldn't say that neutrality is my number one priority (another misunderstanding which folks have attributed to me.) Number one priority is a smooth response (no peaks). EQ'ing screwy response is difficult. EQ'ing a smooth response is easy.

See Soapbox articles written shortly after this website went live: http://www.changstar.com/index.php/board,4.0.html

I think it's important to clarify frame of reference and priorities. It's so when I say the X is a piece of shit, people understand where I am coming from.

Yup, it's a coupler doo-dad exactly as you described. Not anatomically correct, but it works. But so does the silicone tube that Sonove uses. LFF feels that a simulated canal close to being anatomically correct yields the best binaural effect.

Ah O.K. makes sense 
thanks for the info.
One could easily bend the silicone tube in the same way as the ear canal is I reckon and that could have an influence on the correction needed as well.
Silicone seems a better mimicking material as a straight copper tube.

Neutrality is very simple. It's simply a reference, albeit difficult to exactly define subjectively with 100% accuracy, which one tries to shoot for. Subjective impressions of neutrality will vary slightly from audiophile to audiophile. Subjective impressions of what is neutral vary little among recording engineers.

Well put !

I made a recording of some music via an (equalized) T40RP and compared that to the original.
Did the same with other headphones (standard and modded ones)
Also did the same but using white noise.
Analysed the spectrum and listened to the recordings comparing them with the white noise.
Differences are immediately apparent.

Will do more of those in the future, having a rig is more than enlightening when modding away.

EQ'ing screwy response is difficult. EQ'ing a smooth response is easy.

Indeed !
It can even be done analog in a lot of cases.

"What is comes down to is that a neutral system will be the most flexible with the most recordings for most (but not all) people."

See, this makes sense to me.