Go you good thing!

These are damn good headphones when driving them with my FiiO E11 headphone amp, but without an amp they still sound very good, but hey, they're  supposed to be driven by a good amp to perform at their optimum, right, like any headphone?

Some people say the bass in these 580's is huge, but actually no, they don't have huge bass extension at all, they do resolve down to 10hz, but they do not present the bass in a boomy fashion, just tight and controlled; i can hear that they reproduce most if not all relevant bass frequencies, but anyway if i switch my FiiO E11 amp to its second and third setting, well hey, these are capable of delivering any amount of bass, but regardless, in a general sense the bass in these is just right, these Ultrasone 580's do a good job of presenting a pleasing amount of punchy bass and without infringing on the other frequencies.

Some people have said that the 580's produce lots of bass, i say no way, my Denon D1100's have more bass than these, so what does that say, the Denon D1100's extend down to 5hz in the specs and you can easily hear the excessive bass extension very low down.

Overall what's so good about the Ultrasone 580's is that they treat the whole sound spectrum with sheer class, high-definition and clarity, and it gives a very good impression of any bass in the original recordings with a bit of extra extension, but not in a shoddy way, but if the bass in the original recording is more tightly focused and not so deep, then that's exactly what the Ultrasones will give, it all depends on the source music.

Anyway, as-far-as midrange and treble in the Ultrasones, the treble exhibits 'natural' accurate clarity and not in a sibilant or overt manner, but rather with a pleasing realistic tone; i have heard many stereo's turned up too high in the treble range and some people love it, but the Ultrasones do not show excessive or sibilant treble, just a tad brighter than most other conservative headphones.

As-far-as the mid-range is concerned, it is clear and present, no doubt about it, however, if i had to fault it, i would say that the upper midrange is ever so slightly recessed, but most people won't even notice 90% of the time, because for the most part there is still enough detail to be heard there anyway.  

The stereo imaging in these is 'bang-on,' not to shallow, and not to wide, just very realistic with a nice sense of spaciousness without overdoing it.

All-in-all these Ultrasone HFI 580's put in a superb performance when amped, i deem them a rare gem in a world of 'me too' headphones, striking a nice balance between accuracy and high-definition of the whole frequency spectrum. There really is no obvious drawbacks to this headphone, it offers a sense of clarity and excellent overall presentation that sounds very pleasing to the ears...

I spent half an hour comparing these Ultrasones with the Audio Technica ATH-M50's both on the same FiiO E11 amp, and although the M50's do sound generally nice, they seem to lack the overall clarity and definition and stereo imaging of the Ultrasone 580's, and the Audio Technica ATH-M50's have less bass which actually equates to not enough in my book. When putting on the Audio Technica MTH M50's immediately after listening to the Ultrasones, the M50's sound boxy in comparison with less definition, but regardless of that, something about the M50's does still give a sense of intimacy and seemingly nice presentation that sounds good in its own right, and if i had no other option i might use the M50's, but i would definitely say that the Ultrasones are clearly superior in every way over the ATH M50's; the Ultrasone 580's are simply a more refined and professional sounding headphone in every respect IMO.

EDIT: I have just re-edited all of this review after 30 hours burn-in, and all i can say is... OMG! The increase in fidelity is audible. Make sure you do not judge these headphones until you have used them for thirty hours, because the burn-in period transforms the Ultrasone 580 into the best headphone i have ever heard, and i am not generalizing or exaggerating at all; i dare anyone to spend any amount of money up to $2000 on any headphone and amp combination, and yet you will not find a better headphone on the planet than these Ultrasones, i bet my life on it. Forget AKG, forget Audio Technica, forget Sennheiser, forget Beats by Dre, after buying 7 different pairs of headphones plus auditioning pretty much every high-end headphone on the market including all the so-called best audiophile one's, well after 30 hours burn-in these Ultrasone 580's simply excel unashamedly, they are very accurate and high-definition, and the overall sound is nicely balanced, it is almost impossible to fault them. Simply buy a FiiO E11 and these Ultrasone 580's and not much on the planet can beat you, i'm not kidding, Simply wait for the burn-in period and subsequently you will not be disappointed.