Basically, I joined head-fi to finally get some good closed monitoring headphones. The models mentioned thus far in the thread are obvious choices, I am still eyeing Fostex T50RP ( with some mods ) .
I would like to add JVC HA-S 770 to the mix - just released and just ordered, waiting for delivery.. I have its predecessor, supraural HA-S500 that introduced world's first carbon nanotubes diaphragm in a non IEM phones, available from Japan only since July. Check the massive thread for HA-S500 on head-fi, general consensus is that they leave AT ? 50 in the dust. HA-S500 is too fun signature with too cramped soundstage to be useable as such as monitor phone, but from the experience with HA-M750, which is a circumaural as opossed to HA-S500 supraural/on ear, I believe JVC may well have nailed it with HA-S770 as monitoring headphone - it is the superb driver from HA-S500 ( or very similar ) mounted in "everything else" from HA-M750.
http://www.head-fi.org/t/621063/the-new-jvc-ha-s500-40mm-carbon-nanotubes
http://www.head-fi.org/t/637477/jvc-ha-s770-first-over-ear-carbon-nanotubes-headphone
Carbon nanotube diaphragm are FAR superiour to anything used in dynamic phones previously. They can meet , or under certain circumstances, even exceed performance of electrostatics ( Stax is the first brand that springs to mind ) in the treble - so great for analog or hi rez digital recording. One caveat - if you do not believe in burn-in, carbon nanotubes will change that - they really require couple hundred hours of high volume music playing in order to settle down to their final signature.
The dynamic range of carbon nanotubes is second to none - HA-S500 can reproduce the tiniest sound from say a cello while the rest of the orchestra is thundering away - they enabled me to find extremely low level defects in some ultra acclaimed audiophille recordings that went unnoticed before on both Stax Lambda Pro/SRM1MK2 and AKG K 1000.
Will post impressions in the 770 thread once they arrive.