Just registered so I could reply. I decided to get a pair of these kns8400 just to see what I thought. I read most if not all of this thread and they sound like something I'd be interested in.
Some background. I've been playing music since I was about 8. But grew up listening to my dad play in bands since I was born. I'm 32 now and have been recording/mixing for about 12 years. When I was younger and single, I had a bedroom studio set up with event 20/20 monitors using various interfaces over the years.
I'm now married and have two little boys and no bedroom studio. So I do a lot of work on headphones/in-ears. For the last couple of years on etymotic er-4pt's and sennheiser hd280's, through a metric halo 2882 and using a presonus hp4 so I can have multiple headphones hooked up at once. I had never intended on using the 280's for anything other than tracking (they have killer isolation), but use them as a second pair just to see how my mixes translated to them before bouncing a mix and making a cd to test elsewhere. I had finally gotten pretty comfortable with this workflow, but things still didn't translate quite as well as I would like. I have the event monitors and have been trying to figure out a way to set up a room, but that's just out of the question right now.
So I stumble upon these headphones while looking at other monitors. Read some reviews from here and elsewhere and decide why not. They showed up Monday. I was anticipating a bright headphone that I would have to burn in before using. Plugged them in and was surprised.
Maybe I'm used to the detail of my ety's but I found the highs almost recessed and not near as detailed. Mids are great and detailed, but the low mids and lows. Omg they were punchy and detailed. In a way I've never heard any headphones do. The 280's have bass but it's kind if thick and not exactly detailed. And the ety's have plenty of bass, but again are almost surgical and it's hard for in-ears to "hit". These kns8400's punch. I love it. I can finally hear the low mid mud that has been plaguing my mixes and clean it up. And can get the bass guitar and kick drum to play nice and have their own space. I can also do that with the ety's but it never translated like I would like. My mixes where still a bit vague down low, and sometimes there was too much and sometimes not enough. Not anymore.
And while I still don't think these have the high end detail and precision my ety's do, I've found I do appreciate the highs on these. I've never used the venerable yamaha ns10 monitors, but think these may have a similar thing going, but in the highs and mids. Once the mix sounds right on these, it sounds right on other systems.
I still have my other headphones there to compare, but color me impressed. For flat out listening (in)to a great mix, I still wouldn't trade my ety's. But for trying to create that great mix, these do have an edge.
It's almost like the ety's are so clear, you can always hear everything, so it's hard to know what you need to do. With these you have to work to make the mix work, and hear the elements you want to hear, but once you get it right, it's simply right.
These may be the best money I've spent lately. If your intention is to create/mix music give these a shot. If you're interested in great sounding headphones for listening enjoyment, I might suggest you look elsewhere. But for what krk intended I think they hit a homerun.