ES700 for me is my favorite portable can. Guys know how unbelievable great these sound only when you try one. I am willing to bet whatever sound you thought these would sound like will be exceeded.
I used to hate their sound, no matter how long I burned them, they sounded bad. Then I put them aside for couple of weeks and suddenly they started to sound fantastic, especially with vocals!
I guess I overburned them in the beginning...
My only problem with them now is the pads. The original pads are unusable - they hurt too much. WS55 pads are a big step up in comfort, but still can cause pain after a prolonged session.
ESW9 pads are even more comfortable, but they place the drivers further away from the ears, changing the sound too much - the intimate magic in the vocals is gone. The bass becomes a little smudgy too. ES700 still sounds great, but not as good as with WS55 pads.
I guess I still prefer JVC HA-S400 to ES700. These can't be "overburned", it took at least 300 hours to get them to sound as they should.
If I don't use them too long, the diaphragm gets stiff again and they need to be burned again for a few hours.
I especially like how a 17$ pair of HM5 pads turns them into a proper "around ear" headphone, that you can listen to for hours without any pain.
HM5 pads also increase the soundstage greatly, but have the same negative effect on bass as ESW9 pads on ES700 - doesn't sound as tight as before, although still good.