I'm also an XB-700 owner....
...had these beauties for around 8 months now, and never heard such clarity from ANY other headphones!!
first of all...the sound. WOW. 3watt, 50mm drive units delivering stunning bass ranging from an incredible 4hZ (below the human hearing capability!) to treble hitting an incredible 28kHZ! (WAY in excess of hearing ability!) These headphones deliver the most crisp high frequencies imaginable, there is no hissing or sense of "pushing limits" with them, they just deliver and deliver and leave you with a nice case of tinnitis! lol
The bass output will literally shake off your earlobes! enough volume, some Tinie Tempah etc, and you've got a perfect ear massage going on! the bass delivery is powerful, yet very refined. If you are using a decent audio source (ie, anything BUT an ipod or Windows Media Player) you are in for a treat! the only way you can mess up the sound quality is by playing with equalizers when you're completely tone deaf...
The build quality; EXCEPTIONAL. Cast plastic chassis' supporting the drive units mean that there are no nasty rattles, they are ported at the back (behind the headband to prevent obstruction) and are backed in well finished silver plastic.The earpads are made from a marshmallow soft, leather wrapped foam which makes them feel beautiful and soft on your ears; backed with the soft padding across the top of the band, they feel completely weightless! (despite weighing in at nearly quarter a kilo!)
The side parts of the headband mech are made of laser-cut aluminium, and offer a very solid feel. i was actually in an accident in which i was (fortunately!) wearing these headphones, and they managed to stop a solid metal bar passing through the top of my head at 30mph! despite being knocked out and waking up in a puddle of blood, the headphones only suffered a tear in the leather and a bit of scuffing on the right-side of the band. all reviews saying these feel "fragile" or "brittle"....are talking utter SH**E! lol
So, to sum up these eardrum blasting, wallet busting, life saving (literally) headphones, i would score them 10 out of 10 without a doubt!