Heya,

Sounds like the Ultrasone PRO 650 is more up to your needs.

Or the 2500 if you want open-air for increased sound stage and some smoother treble experience.

Very best,

I love Ultrasones myself (I have the Pro 900 and HFI-780), but if classical is your primary genre I wouldn't rule out other brands.  Ultrasones are excellent for DnB and good for rock, but a lot of people don't enjoy them for classical.  The higher end ones and open-back ones (Pro 2900, Proline 750, etc.) will be better than the others in the Ultrasone lineup for that purpose, but I'd still recommend considering Sennheisers, AKGs, Beyerdynamics and others.  Every brand could be said to be "a new experience."  Maybe you would still prefer Ultrasones, just don't close your mind to other options.

Pro900 is excellent with piano and not bad for classical in general, but yes, its not pro900 primary use.

Pro2900 for an excellent all rounder, but actually much more than 300$.

I have never heard pro750, must be very good, but i don't know differences between 900 et 750.

My king for classical is HD800, but i also like HD600/650 in this register.

The Pro 750's are my primary can right now (until my D5000's come!) and they're awesome headphones, but they don't seem to match up with the genres you said you enjoy most. The Pro 750's dominate when it comes to things like electronic music (especially ones with a strong bass emphasis like dnb or dubstep). It's not to say that they don't sound fantastic with classical, but it isn't optimal. If you want to listen to things like classical and rock, I'd get headphones that are best when playing classical and rock.

I am actually playing classical with them right now. I'm using a little reversible partially open-back mod I thought of a week or so ago, and it helps make classical sound nice, but still not as much as headphones designed for classical.

If your heart is set on the pro 750's, you will love how they sound with the genres you are talking about, but maybe not quite as much as a headphone more suited to those genres.

I'm just going to give my dissenting opinion here. Personally, I found Ultrasone to be one of my least favorite headphone brands ever. I haven't listened to any of their top shelf headphones personally, but I seriously disliked their lower end and it seems like everything they offer doesn't solve the problems I have with their headphones. Sound signature may be fluid, but their stock signature sounded highly unnatural to me with oddly high energy highs and off-sounding mids. I felt they are one of the most genre constrained headphones I had ever heard, only sounding "right" when listening to electronic or other bass heavy genres of music -- if you asked me to give an antithesis headphone of an all-arounder, Ultrasone is very high on my list with their highly colored sound and odd imaging. You say they don't sound "fantastic" while listening to classical, I say they sound outright mediocre at classical. Their bass was nice and tight and they sound very good for the electronic/d&b genres, but that's the only praise I'll give them.

Their high end headphones measure poorly in an objective sense in terms of distortion and and they have odd ringing that I'm dead certain would show in waterfall CSD plots. They still retain that odd high energy in frequency response curves. 

That said, as you can see, some people like the sound of Ultrasones and disagree with me. I would say 100%, though, never buy an Ultrasone without listening to one first. I would have been highly disappointed if I had purchased an Ultrasone and not listened to someone else's first. Just as some people love Grados and others hate Grados, I feel Ultrasone is a very similar brand. You can feel free to jump right in, but I'd feel like it is taking a chance.

I suppose if you want something different, they're definitely different.