[Annirak]

The upgrade bug bit me over Christmas.  I preordered a USB DAC with balanced outputs.  My existing headphones won't either support that or do it justice.
 
So, my requirements:

1. Balanced, or easy to re-cable for balanced.  
2. Circumaural configuration
3. Detachable cable (this ties into re-cabling)
4. All metal structural components (therein lies a story for another time)
5. All components replaceable (Another story for another time)
6. Comfortable fit (I know this is subjective, but some headphones have a bad reputation with regards to comfort)

 
My preferences:

1. Factory balanced (no DIY re-cabling)
2. Closed back
3. Possible to audition in the UK

 
My listening preferences in order of use:

1. Electronica
2. Rock
3. Pop
4. Metal

 
While I am willing to mod headphones (Cabling, damping, driver mods, etc).  I'm handy with a soldering iron, I can source my own parts, and I'll have access to a 3D printer shortly.  While I would rather not have to mod my headphones, I'm totally capable of it, if it really would be better value.
 
I wouldn't spend more than $700.  That's not my actual budget; but I'm interested in suggestions up to that level.  A quality DAC deserves quality headphones.
 
I've owned a pair of Shure SRH750DJ and, while I like the sound quality, I don't like the fit or construction.

 

[Annirak]

I realise I didn't specify.  They should be Circumaural cans (around ear).