Okay, guys thank you all so much for the responses! You've really helped my decide what to do for the best, and saved me some money, I think :D I'm gonna buy an amp/DAC for now, to drive the Pro DJs, then later on get the Sennheisers.   Thanks again :)

Are they still worth the purchase if I were to get no amp for a while, or perhaps a relatively inexpensive (ie. FiiO e7) amp/DAC combo? I just don't want to spend so much cash on the headphone+amp+DACs... Might it be better to invest in a decent amp/DAC for the DJ Pros, then upgrade headphones...

Wow, thanks for all the replies!   I'm now thinking it's much better to spend the money on a good amp and DAC than replace the cables (to start with, at least).   @tomb: I'll bear the cable in mind for later :) Thanks for that link, btw, it was useful!   @tdockweiler: I heard that...

Haha, well it's good to hear I don't need to spend money on cables! I'll have a look at the Asgard, see if I can find a reasonably priced second hand version somewhere, thanks :)   I've been doing a bit more reading, and how important would getting a DAC be? If it's not included in the...

So I'm looking to upgrade from my Koss DJ Pro 100s, and it looks like the HD 600s are the perfect next step. I'm going to be using them for music production, as well as general listening, so I'm looking for as flat a frequency response and as 'true' a sound as possible.   I have a couple of...