I think I'm right in saying the Senn HD25 SP 'ii' is just the current version and there isn't a major difference from the non 'ii' - that is if you can still buy that old version.
However I know they can't hold a candle to the Senn HD25 ii(non SP) which are £130-ish, and even then many people find they have to recable them to get the best out of them. Admitedly this would have been for music listening rather than DJ-ing.
The AKG K181 DJ can be bought for £69 delivered, and is said to be a contender for the best DJ headphone, along with Technics RP DH1200(£95), Pioneer HDJ-1000(£130), and the Sony MDR-V700 DJ(£80).
Also Equation Audio RP21 is supposed to be a very good DJ headphone which if it can compete with others would be a top bargain as its only £45.
Another possibility is the AKG K518(£37) being the K181's little brother and is smaller and supra aural like the Senn HD25 as opposed to all the others mentioned which are all circum aural.
I am also trying to make up my mind on some DJ headphones and so have done a bit of research /\

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