The K530 are quite hard to find even in Austria (AKG is an Austrian company - at least partly). Same goes for the K324P which seem to be a CX300 variation. I have them now for some days and like them better than any of my existing phones for home listening all of which fall more or less in the same price region - Senn HD555, HD485, AKG K271.
They sound big, with deep bass that's never boomy, voices are sweet and highs are detailed but never aggressive. They are easy enough to be driven from iPod or laptop jack but definitely benefit from a dedicated amp. The looks are a matter of taste. Cannot decide if i find them retro or futuristic. They make a good match with my white MacBook.
Compared with HD555: I love AND hate the HD555, listen to all kinds of music and I love them for how they present small setting, female voices, Jazz etc. but tune to some not so well recorded aggressive rock and they just suck. The bass section of the K530 blows the Senn away and overall the sound more grown up.
Compared with HD485:
Both are pretty much the same price over here. Got the HD485 for 85 Euro and the the K530 for 82 online. The HD485s deliver where the HD555 lack - bass. They're just a fun listen, easy to drive and never aggressive, but at a price: the highs are rolled off, there's less detail, the overall presentation is less thrilling and engaging than the K530. Both 555 and 485 to me have the same overall "Sennheiser" sound signature - though they are quite different - and I'm now sure I like the AKG approach better....
Compared with K271:
I got rid of them simply because I now don't need closed fullsized phones anymore and they are a little bass shy compared to the K530, that's all.
So for now I'll use the the K530 "in-house". The K81DJs are my semi-portable option and they're still fantastic price/value - just a little too uncomfortable for long sessions. Whereas the Senn PX100 don't get much use these days I still use the CX300 every day on the street.
BTW, if anyone tried the K324P I would be interested if they're different from the CX300?