Good headphones for electronica?

I'm sure this question has been asked a million times before, although I figure it would be best to get an up-to-date answer as opposed to trying to get information from month-old posts.

I'm looking for some closed-back headphones in the region of £100-150, preferably with as low impedance as possible in order to minimise the need for an amp. In addition to this, I'd like a decent portable amp to drive them, although preferably something as cheap as is possible in order to obtain decent SQ when it comes to the amp.

They would be listened to (via the amp) through a Cowon S9, and the music I mainly listen to is Trance and other electronica (Basically anything from YouTube - Chicane - No Ordinary Morning and YouTube - Oceanlab - Ashes (HD) to YouTube - Marc Dawn - Expander (Flutlicht Remix) and YouTube - Wittendoerfer - Anywhere But Here (DJ Space Raven remix)).

They would also be used for films and the odd Video Game (So a good sound stage - I'm using a sound card with cmss3d, if that helps anyone - would be a nice plus, however it is not my first priority). Delivery to the UK is also a must.

I'm tempted by Ultrasones, from posts I've read on here. However, I'm unsure as to which ones would be ideal and whether or not they'd be worth it. The Proline 2500s seem decent for £165, however I'm wondering whether they're good for what I need.

Feel free to suggest anything or point out any mistakes I've made here - I tried to do some research but there is only so much you can read. As long as it's within my price range and you can back it up (i.e. tell me what they sound like to listen to as opposed to just saying "Sennheiser X" or "AKG Y"). I'm not looking to spend as much as I possibly can either, so I'm perfectly willing to spend alot less.

Again, I apologise if I've made any mistakes or false assumptions here. I'm hardly an audiophile.

Ok - thanks for the responses -, I'm debating between the SRH840 and Ultrasone HFI580's now. Slightly leaning towards the Ultrasones simply based on price (They would leave me with a bit more to spend on an amp), although Acix seems to suggest them in most threads I've looked at, heh.

However, I'd like to know the difference between them - what sort of difference in sound would the wider frequency response on the 840's actually produce (If any), and what difference would the lower impedance on the Ultrasones make (Again, if any).

What is the sound stage like on either of these? Any major differences or about the same?

Also, any other suggestions for an amp or is what Dultsi said pretty much spot-on?

I actually looked at the 680, but the high impedance put me off - I wasn't sure how good an amp I'd need for them. They both seem similarily priced, does anyone know the actual difference between them? And what about the 780, is that just a 680 with lower impedance and more bass?

Gone with the hfi-780's (Managed to get ahold of them for £120, which was great) and the Fiio E5 amp (I don't think I'd really be using the portable amp often enough to warrant spending a lot more on one).

Just got to wait for them to arrive now.

Thanks for the help people.