@Dan Clark And if you ever consider some type of open variant, make sure it is something like monotone black or gun metal OK, I'm done making my demands... for now.An open version will be an instant buy for me
Okay, I'm going to play Devil's Advocate here with @amirm.
AKG K371 EQ'd $149
Sennheiser HD600/650 EQ'd $400
This product (no ED necessary) $4,000
Please compare and contrast.
Obviously, if you have the money (if you're rich) and you're a headphone lover, $4,000 is probably not that much. If I won the lottery, I'd buy a pair.
But can the extra expense genuinely be justified for people with 'normal' bank balances?
Just how close do those other two, cheaper headphone come to this?
Senn 650 are only really $200 (Drop 6XX).
Here you're paying for things like top comfort, relatively low weight, build quality, solid materials, driver type/implementation (flat imp., ultra low distortion), driver size (soundstage), harman target ootb (soundstage/accuracy), good time domain characteristics, good eq-ability etc. Many of these characteristics may be found in other headphones but as far as what's available now this is the only headphone with almost all of them in one package.
It could still have potential deal-breaking flaws in your case, for example many people find DCA headphones very strict with fitting (wearing glasses, facial hair etc may not result in the best seal) and thus may have a sonic impact if that affects your enjoyment. They are also closed, which personally does not work well for me because I don't like the sensation of my ears being hot/blocked and it also exacerbates my inner ear disease. So a headphone that I cannot be comfortable wearing for more than 20-60 minutes is not a good purchase for me, since my usage almost always exceeds that time. There could be deal breaking things like this for you even if it is on-paper perfect.
FR is still the greatest parameter when it comes to enjoyment but any of these other factors this could be the "last 5-30%" you're missing of your subjective enjoyment and some of that could be objective gain. It can be a significant difference but whether or not that's justified will always be a personal decision. Almost any luxury purchase will never justify the price premium for what you get and it is your subjective desire that ultimate decision maker. No different from buying $50k+ speakers or a Lambourghini. Some people think $4000 headphones that may last for years and have some resell value is an absolutely ridiculous purchase, but will happily spend that in just 1 year to shorten their lifespan drinking weekly at the bar. With headphones I definitely think 99.9% of people can satisfy at least 80%+ of their theoretical max enjoyment with an existing model under $500, or even less if they use EQ.
I'd say the best way to know for sure is simply trying/auditioning a multitude of highly rated headphones from various brands (especially other DCA ones), playing with EQ on them an seeing what features increase your enjoyment or the usability the most. Then you can use the common denominators to find what will most likely suit you.