One of the closest in my memory is probably the Sennheiser Momentum, although I think Momentum has more bass, so it might not be the absolute closest headphone.
Audeze LCD-2 lol
Not identical, but share some similarities in my opinion. Ultrasone Pro750, it does have more bass than the Sennhs, but the soundstage is pretty good for a closed can, with an energetic sound signature.
Mod some Fostex t50rp