A few more thoughts after more listening, producing, and comparing the 4z to my monitors. I know I’m talking a lot about production here, so I appreciate your patience with my ramble. Perhaps I should post this in a production forum.
Speakers have an undeniable advantage in terms of 3D/‘holographic’ sound that you can almost reach out and touch. My monitors still sound very nice, and in some ways, they sound even more pleasant than my headphones. They’re the reason why no pair of headphones priced under $3500 sounded acceptable to me. But as I said before, they are all over the place in terms of bass response (in my small room), and the sound also suffers from ‘booming’ bass reverberation and other issues. I find that it sounds very pleasing, but that it is nowhere near as revealing and accurate as the 4z.
So far, that’s what I predicted (hoped for). But beyond that, the 4z’s ability to pick up the most minute distortion was a revelation. I’m not talking about obvious, clipping, or grumbling distortion, but extremely subtle distortion that occurs when layering too many sounds of similar frequencies, slightly reducing the fidelity of the mix. If any sound distorts even a tiny bit, the 4z will tell me - and when I then fix these small sources of distortion, the resulting mixdown sounds better even on ‘affordable’ systems (such as my AirPods).
As a small example: I was using the highest oversampling setting (32x) on my limiter for my final exports. Using the 4z, I noticed that oversampling settings higher than 8x produce a very slight ‘ringing’ distortion on the sub of any big, boomy dance kick! I can now notice it on my other systems too, and have adjusted my settings accordingly. But I never heard it before, and the 4z just made it blindingly obvious, impossible to miss.
Listening to music from different producers with the 4z, it becomes apparent that few dance producers have access to a full-range system that can reproduce the deepest bass tones (<30 Hz) accurately. Most tracks simply don’t go that deep, and sound slightly band-limited on the 4z. That’s not to say they sound bad, but certain producers, like Deadmau5 (and certainly the top pop producers), use the full spectrum, which adds a glorious extra sheen of bassiness and professionalism, which again, can be heard even on lesser systems (it’s just not as obvious as with the 4z).
It’s interesting how people generally call the 4z dark, but some people find them too bright.
I agree that other pairs of headphones (such as the HD800S) definitely have a more ‘airy’ signature in the treble, and a wider soundstage. I also agree that it would be very pleasant to have the mids/bass of the 4z with such an ‘open’ and ‘airy’ top end. But, crucially, I do not find the 4z ‘dark’ in the sense that treble is subdued or missing. I can still tell exactly how much treble exists in tracks. I was worried that the 4z would be too “hifi” sounding and insufficiently neutral, but it functions so much better as a reference than my monitors do, that these worries have evaporated.
BTW, I’m wondering why most of you guys searching for the perfect cans seem not to be interested in EQ to modify the sound signature. Here is a quote from the RME ADI-2 Pro FS user manual that I found interesting:
“While no equalization as well as listening only straight linear has been a mantra for many years, research has proven that no ears are identical, and that especially in near-field listening (with phones) the biological differences alone make individual equalization mandatory. No two pairs of ears hear the same thing, that’s a fact. Additionally personal taste makes people like different sound signatures, which can easily be copied or made more similar (equalized…) on different headphones using a good EQ. The advantages of using an EQ outweigh any alleged disadvantages - which so often turn out to be wrong at closer inspection.”
I can’t comment from first-hand experience on how accurate this is, but I generally trust these guys to know what they’re talking about.
I would use Audeze’s Reveal plug-in, but I can’t think of a way to have it affect only my headphone output (not the monitors). So, when I receive the ADI-2 Pro FS, I intend to experiment with its per-output EQ possibilities.
its next to Popeye for me 
i hope you dont have beef with them.
