The 558s are excellent all rounders, and from what I hear they can be modded to near 598 levels. If you want the tank Beyers I've heard nice things about the DT770, and you can get those in 32ohm flavors which will be fine out of anything that doesn't plug into a wall. Can't vouch for the DT770, but I do have one of their models on my wish list.
The Ultrasone HFI-580/DJ1 headphones are pretty good, but not as comfortable as the 5x9 series. They clamp more, and will leave your ears warm after a while. They are great cans, but truly excel at electronica and bassy music. They can do other music just fine as well, but they can be a bit bright. IE: treble can be a tad strong in some songs. They are built very well, and have this nice heft to them. At 120 dollars you can't go wrong. I can vouch for these personally.
If the 558s sound anywhere close to my 598s... I whole heartedly recommend you get them. Once again. I point out that with a bit of modding you can get them to sound like the 598.





















