I have the K240 Studio, been burning it in for a couple days now.
I know there have to be tons of reviews on this thing by now but just figured I'd give my thoughts on it, coming from a 280 Pro and compared to my new SRH440.
The first thing is that the K240 is definitely not netural...except the mids, which are extremely organic in nature. It has awesome high frequency extension, the best I've heard in a headphone yet, and the semi-open nature of the headphone lends itself to a much better soundstage than I've heard from either of my other closed cans. The treble definitely has a spike at 10 kHz, maybe by around 5 dB, which is what the headroom raw plot seems to indicate. Beyond that is nice smooth extended highs that will instantly show you just how bad your MP3s sound compared to lossless format music. The bass is very mid-bass and upper-bass focused, and there isn't a lot of sub-bass. It's there, but it's quite subtle. So the overall presentation is warm bass (some people might call it muddy or sloppy but I disagree on them being muddy, they don't bleed into the mids much), with natural mids that are never harsh unless the recording engineer decided they should be, and glossy extended treble. They are a pleasure to listen to and great for vocal tracking as long as you don't turn the cans up too much. Great headphones for home listening in a quiet environment as there is very little isolation, as long as your ears don't get fatigued from the treble spike. It's just tolerable enough for me, and kind of nice if you get used to it.
I'm going to end up giving them to my dad as a gift. He has the original K140 from the 70s that he bought back in the day. They still work, but they aren't with me right now so I can't compare them to my more flat sounding headphones at this moment. I don't think they use the sextett drivers anyway.
Great headphones especially for the $$. Just not for bassheads at all.
Edited by metal571 - 4/9/14 at 12:57pm