AKG Headphones: New K272 HD vs K702 vs Beyer ?

I'm not that familiar with the AKG headphones, but they seem to get high praise when I do see a comment about them. I know the K701's and K702's are the usual contenders, but has anyone compared these to the newer AKG offerings like the K272HD?

Also, has anyone compared the AKG cans to the Beyer Dynamic DT880's?

Right now I'm using a pair of Sennheiser HD595 phones with a dedicated headphone amp by G&W. I think they sound pretty good and of course their character changes with different interconnects between the source and amp. My goal is to improve on the Sennheisers with phones that may be more detailed and have a touch deeper bass. I don't find the Sennheiser 595's particularly lacking... the fact that I'm getting such good results that it has me curious to try other headphones that may be even better. I mainly want natural sounding phones that are great in the midrange and pretty good elsewhere.
You should probably go sift through the input over at headfi.org Using the search engine you can get a general overview of the SQ of each of the cans you are asking about (take all with a bag of salt as far as specifics). I can broadly tell you about the K701's and 702's which is the only ones you are asking about that I have direct experience with. They are identical, except for the appearance and that the 702 comes with a detachable cord which is handy if you want to use an aftermarket cord or alter between balanced and conventional connections. The SQ of the two models are supposedly identical though (same drivers and housing). I think the 701 comes with a plastic tray to set them down in, and the 702 does not. They are open-backed cans so have a very airy presentation. I would say they are definitely cans that definitely require a good amp with some current to make them sound their best. If you are just plugging into a jack off a conventional amp that's been padded down and filtered for headphone use (not all are so veiled) then I'd look to another phone as you'll probably be disappointed (they might sound a bit thin and not very dynamic). What they do very well, with a great headphone amp, is in rendering detail, clarity and soundstaging (big). I haven't heard the Beyer's and the Senn's so would only be goin off hearsay and you can get plenty of that over at headfi. I would confidently say they are quite different from either one. Where I found the AKG's lacking was in the low end, and especially so if you don't have a good amp pushing them...even with, you may still find them to be not the last word in low end extension. I'll leave it to those with direct experience to comment on the others you are asking about. I've ended up with Grado GS1000's which have much of the qualities of the 701/702's (the same sort of airy delicacy, but not really "delicate" - they have more impact and more extension). They are not like the rest of the Grado line, so if you use even an RS1 as a point of reference you'd be off base. I wouldn't use them for anything heavy-hitting though. It may help to mention what you'll be using for an amp, and what you like to listen to on phones.

I figured out that lack of bass in AKG K701 is diminishable with good headphone amp. I now use SPL 2Control. I used to have the same one as yours Cyber 20 but I sold it.
I used to have the same one as yours Cyber 20 but I sold it.

I'm not using a Cyber 20 (sold a while ago). I'm using a maxxed out Woo Audio WA6SE. Love it. I concur that the performance of the 701/702 has the potential to leap ahead with the right amp. It still wasn't the answer for my ears so I sold my 702. Plenty of folks love'em though...mine is only one opinion.
I have brand new pair of 702's and think they're fantastic. I agree that with the right amp, they take a leap ahead. They are also the most comfortable cans I've had on my head, moreso than even Sennheisers. I had Blue Jeans Cable make me a 15' cable for them and they sound much better with this cable than with the original. My problem is I'm not using them. I thought I would use them more than I do, and may be forced to sell them, although I've only had them for two weeks now. It took forever to get them as they were on back order and came straight from Austria.
i still love them since I've heard on my music that I haven't heard ever before!