Okay, so to start this off and focus on the brunt of this. I own a Fostex T50RP MK2, MK2 modded revision by Mayflower Electronics, MK3(Shure 1540 Pads), the AKG K7xx, DT880(premium) 600, and previously the HE400S, HE560, and HE400i. So, in terms of sound signature, the best one I have heard so far was the 560's, but the Hifimans are terribly uncomfortable both in terms of how they sit on my ears, pressure with my glasses, and also the weight. DT880s are comfortable, sort of, but after two hours of use, the metal band in the headband would begin to cause pain and discomfort. The DT880 in terms of sound is--very similar to the K7xx, very lifeless to my ears and as opposed to a lot of other opinions that exist; veiled, not too fun at all. My favorite headphones so far in terms of sound, but not quite there for me, but excellent in comfort(could use slightly larger ear cup size) and weight is the T50RP MK3's. They also have what I'd consider the most "fun" signature of all the headphones I've tried. The HE400S were much the same how I felt in sound with the K7xx's, the DT880 only being slightly better, and then the 560s and 400i being a marked improvement, but still not what I am looking for.
AMP/DAC that I use is either the following: JDSLabs Element, Objective 2+RevB, Schiit Magni 3 + Modi 2 Uber, and the Jotunheim Multibit. Never tried tube anything, it'd be a rabbit hole of expensiveness(like this hobby isn't already that as is, next to firearms and keyboards).
In terms of my sound preferences, as far as I can tell - I love treble, exceptional amounts of treble and detail. Concussive, fast bass, not rumbling, and slightly forward mids, as well as maintaining some extended soundstage, but with positioning being far, far more important to my ears than expansive stages. Not exactly sure what categories or headphones can fulfill those roles. So I present it to you, the Massdrop audiophile community.
As far as I can tell, in terms of the higher end headphones ,the TH900, would probably satisfy me and my needs, but at the same time is too expensive to justify at the time being, so anything below $1000 is what I am looking for.
So, recommend away! Hopefully I provided a degree of insight in to my likes, comfort issues, and preferences.