[Deterministic NL]

I'm not sure why but I'm looking to add another set of cans to my harem. Right now I have Sennheiser HD650, Sony MDR-V6, and Bose QC-15 (strictly for airplanes and trains).
 
The HD650's only play nice with one system I have and I have many systems.  Think obsessive / compulsive.  They are comfortable beyond belief. I like the way they cover the whole ear.
 
I absolutely love the Sony MDR-V6.  They are amazing headphones.  And as I said I have Bose noise cancelers in the laptop bag for travel.  I actually like them for watching videos on the iPad or casual music listening.
 
I'm considering Sennheiser HD598 for the "middle" pair but I think I'm overlooking a lot of possibilities.   Budget is no issue however I don't want to spend more than I did on the 650's.  When I got the 650's I came dangerously close to getting the 598's and had I understood more about high impedance I probably would have gotten the 598's.
 
Also I live in Japan if there are any hot Asian cans anybody knows about. 
 
So basically I'm looking for the sound of the MDR-V6 with the "cover the whole ear" comfort of the HD650's. 
 
All ideas appreciated. 
 
My systems and components are (that have a headphone input):
 
All lean towards lower impedance other than the Crack.
 
Bottlehead Crack amp
Bottlehead SEX amp
Fisher 500C
Schiit Modi / Magni combo (Schiit Stack)
Fiio E17
Fioo E7
Fiio E09K
Fiio E12DIY
ODAC
Nuforce UDAC 2 and 2SE
HiFiMEDiy Dac
Nexus 7 with any of the above mentioned DAC's
MacbookAir with above mentioned DAC's
Dell Linux Laptop with above mentioned DAC's

 

[Me x3]

Hi,

What about AudioTechnica AD900X?