Pros: Extremely detailed, tight and punchy bass, comfortable (velour), detachable cable, very good soundstage, accessories, very easy to drive, look great
Cons: Shortest straight cable in existence, highs can be too aggressive sometimes, aluminum cups can get scratched easily
I've had quite a few of Ultrasones, which include the HFI 580, HFI 2400, PRO 900 and the PRO 750. I prefer the 750 over all of these. They have a very balanced sound with amazing tight bass and an edge in the highs. Mids are very forward for an Ultrasone, though I find the highs to be slightly too aggressive and overbearing at times, though it's not as bad as most people say they are. It's a very fun headphone, without the bass drowning the music like the PRO 900 and the ultra recessed mids of the HFI 580. I also think they are very comfortable because of the velour padding and that they look badass. These are extremely easy to drive headphones, and I don't understand why people say these need a lot of power to run, as I can run it directly through my MacBook Air and get amazing results. Out of my EF2A amp, I don't hear much of a difference at all compared to unamped. I will buy a small E6 for these to maybe get a slightly louder sound out of my smartphone, but if you cannot afford an amp for these, don't worry, they run fine without one. I need to get a cable extender because the straight cable is very short. Comes with a sturdy carrying case, two cables (one straight, one coiled), a manual, a test CD and an extra set of velour pads. It's an amazing headphone, highly recommended.