This is a review of one of my favorite headphones. I've been using it for quite awhile and love it. KRK seems to have gotten nearly everything right with this headphone. I'd feel really bad if I didn't review such a great (and severely overlooked) headphone. This time around I'm not going to over-analyze everything and these are basically just some impressions and comments. It's a bit all over the place, so feel free to skip down to the "TL ; DR" edition if you don't want to read my rambling.
Late last year I bought the KRK KNS-8400 and posted a positive review of them. I liked them a lot despite them not having my favorite signature. It was one of the very few headphones I didn't immediately like and it needed about three days of burn-in to sound good and to smooth out it's treble. I ended up selling it because I rarely used any closed headphones and I had so many open headphones at the time. I was so impressed with it when I had it that I even went out and bought another Shure SRH-840 just to compare them! The SRH-840 lost.
I was curious about the KRK KNS-6400 after seeing it's frequency graphs and took a chance at my local Guitar Center. It was a risk because my location didn't accept any returns. They run about $99. I imagined there would be a huge drop in sound quality with the step down. Was I ever wrong!
I got them home and immediately liked them and was quite impressed. They didn't need ANY burn-in AT ALL to sound good! My first KRK KNS-8400 needed about three days.
OK, this may sound silly, but all my music sounds exactly how I always remembered it. Is that a bad thing? There are songs I've listened to hundreds of times and they sound like how they should. These things don't really alter the music much and try to make it better than it really is. Despite this, they're not boring and music is still engaging and fun to listen to on them. Generally some studio monitors can be a snore fest, but not these.
I don't think they're perfectly neutral (but what headphone is? My K601 sure seems like it), but close enough for me. If anything, there may be a VERY slight boost in the mids somewhere. Notice I said SLIGHTLY. I don't really think they should be put into the group of headphones with forward mids like the DJ100, ATH-AD2000 and HD-598. The mids are just quite engaging and even more so than the KRK KNS-8400, or so it seems. I'd have to compare them side by side.
I've been listening to these so much since I got them that I now have a good feeling of how they're supposed to sound. Sometimes they sound like garbage and other times very, very impressive. Why? Well, it all depends on the recording. A few weeks ago I switched from another headphone and put these on and I remember thinking "Not so clear..." I got the wrong impression that it was the headphone, but it's absolutely NOT. It's the recording. Even some of my lossless tracks sound like garbage. The other headphone just wasn't as revealing of how bad the song was. I don't buy a lot of stuff on Itunes, but it's easy to tell which tracks are downloaded from Itunes! I sure wish it was easier to buy on CD some of my favorite ambient music. They're revealing, but not overkill. If you normally hate studio monitors, give these a try.
I haven't compared the two KRK headphones side by side, but the KRK KNS-6400 sounds more natural than the KRK KNS-8400. It should be a better match perhaps for those that just want to enjoy their music and not analyze it 100% of the time. The 8400 is the one that seems to have the more extended treble. The difference between the two is kind of like the difference between the K601 and K702 kind of. The K702 has some similarities to the KRK KNS-8400!
The part I don't get is that when I listened to the KRK KNS-6400 I immediately noticed that it gave me the feeling of more bass than the 8400. The bass had more impact, when I almost never got this impression with the 8400. At times I questioned if my 8400 was a lemon, but everything else was fine. I don't know if KRK made any changes in the models, but it's possible. I always said that the HD-598 had a smooth sounding signature (despite the forward mids!), but this 6400 is even smoother! Nothing jumps out at you and will annoy your ears. To me, it's just an enjoyable studio monitor that won't bore you to death. In my HD-598 review I said that if I were to describe it with one word, it'd be "Smooth". For the KNS-6400, it'd be "Accurate". All my music is exactly how it should be.
I did say that the headphone doesn't change the music. OK, maybe a tad. One thing I've noticed is that on some very brightly recorded and harsh tracks, they're made a little more bearable on the KRK KNS-6400 compared to the 8400. I guess it seems to tame them just very slightly. On the K702, DT-880 and even the KRK KNS-8400 it didn't touch them at all ever. I have no problem with the 6400 doing this very slightly. Some many not agree with what I'm saying. Many people seem to think it's the headphones fault for all the harsh sounding songs, when it's just the recording itself. I have about a dozen songs from a Japanese singer named Hitomi that just about annoy me on nearly any headphone due to how they're recorded. It got so bad I just removed from my collection.
Another very strange thing I noticed is that the KRK KNS-6400 has a very impressive soundstage for a closed headphone! I felt that my Koss Pro DJ 100 had one of the best (under $200 closed), but this may have that beat! At times I'm even fooled into thinking I have an open headphone! I don't EVER recall this with my KRK KNS-8400 and originally I complained that the 8400 had just an OK soundstage. One thing that could help is that the KRK KNS-6400 drivers seem to be angled!! Nice going KRK! Of course it all depends on the recording. Some CDs with nothing but nature sounds feel as if I'm actually caught in a real life thunderstorm with the rain all around me. Speaking of that, these things are so nice for ambient music such as Helios. With movies I sometimes forget I have a closed headphone on my head.
On the first day I found them fairly uncomfortable. It seems that they need some time to adjust to your ears. I stretched out the pads slightly and the problem went away. By the time the problem was fixed I had already ordered the 8400's memory foam pads. The KNS-8400 memory foam pads fit on the 6400!
I'll just come out and say it that the 8400 and 6400 (with memory foam pads) are some of the most comfortable headphones ever made. The only negative for me is that my on my head, the headband seems to extend 1 1/2 inches on each side. They look a big goofy on my head. I tried and failed to use these during weight lifting (at home!). That's too bad. They're secure on my head, but using them during the bench press is probably asking too much! People with bigger heads will love the fit I think. I could probably wear these all day without any pain.
I always said that the KRK KNS-8400 was one of the clearest sounding headphones I've ever heard. You'd think that since the 6400 costs $50 less there would be a massive drop in sound clarity or overall sound. Not really. I don't really feel like the sound clarity drops much. Still crystal clear. I think on the KNS-8400 there is more treble extension. I'm not sure what else. I'd have to compare them side by side again. I most definitely prefer the mids on the KNS-6400.
Other than the soundstage and sound clarity, the next best thing about the KNS-6400 is the detail! I could call this thing a detail monster with no problem. It has more detail than the K601, K702, DJ100, MDR-V6, Sextett, K240 Studio and basically many others I've tried. I've done numerous side by side comparisons. There is this song I often use for reference that has 5 metallic sounds on the left that are very, very faint. On the HD-650 I had I could only hear about 3 of them, but only if I EQ down the bass. Yes, really. On the KRK KNS-6400 I hear 5 or 6 clear as a bell. Quite impressive. Basically if you want to hear everything that's in a recording for cheap, this will do the trick. I always thought maybe that the more you spend, the more detail you'd be able to hear, but price doesn't seem to mean much when it comes to this. Sometimes. The KRK KNS-8400 already beat out my Shure SRH-840 in nearly every area, so I guess now I'll need to compare the KRK headphones to the Shure SRH-940. I bet they can hold up fairly well! Maybe not.
For probably a year I was always looking for a headphone that could dethrone my DJ100 as my favorite "fun" headphone. This just might be it. The DJ100 is still addicting and needs an amp and this doesn't. It sounds perfectly OK straight out of my Ipod Touch.
You know what? I hate the dozens of PERFECT reviews where people are afraid of pointing out negatives of their favorite headphones. I hate it, but as it is right now and with weeks of listening, the KRK KNS-6400 is about as perfect as you can get. It's one negative is that I still hate it's cable. It seems to be very durable, but still yet seems to tangle up so easily and you can hear it move around when the headphones are not in use, but over your ears. It's too bad it would be nearly impossible to recable these. I may just buy the coiled cable. I'm sure the wiring inside is something high quality, but it's really one of the most annoying cables there is. You could also wrap it around something and when unraveled it'll probably retain that shape for a day. I bet I could run over it with my car and it'll still be working though.
One nice thing about this headphone also, is that it may be the perfect closed competitive gaming headphone! It has some great imaging, a good soundstage, tons of detail and isn't super bass heavy. Not bass light or even close. I don't like closed headphones for gaming, but if I did need one, this would be it.
Accurate Bass, Good Mids, Fairly unforgiving, Tons of detail, Comfort, Sound clarity, Imaging, Very good soundstage for being closed!, Smooth treble and overall sound signature, Good for nearly every genre, Accurate, No excessive clamping force, Great price ($99!), Angled drivers, Non-fatiguing, Amazing for female vocals (especially Jpop/Cantopop)
Cable is annoying. Pads are kind of tricky to replace (maybe I'm doing it wrong).
So far these are the best unamped closed headphones I've heard yet under $200. Ever since getting these I've rarely used my K601 and HD-598. Something about how they sound makes me keep going back to them. The HD-598 is more fun to listen to, but doesn't quite sound as clear sometimes, but is more forgiving. Less detailed for sure.
Now I guess this will be what I'll be using until I find something better. Perhaps the Shure SRH-940? Who knows.
For $99, this headphone is a steal. I think it's safe to say I prefer it to the KRK KNS-8400! Sadly, few people on here seem to want to bother trying headphones that few people have heard. The KRKs and Koss Pro DJ100 are severely under-appreciated headphones. Sometimes all these inexpensive headphones make me wonder why I bother with $300+ headphones. If I had to only use the KRK KNS-6400 as my primary headphone, I'd be perfectly satisfied.
Edited by tdockweiler - 6/30/11 at 7:35pm