[Katun]

 
 
 
Quote:

It's nice how we all prefer different sounding headphones and signatures. My opinion also is that for these you just pick what sound signature you prefer. Both are good. I actually now prefer the 6400 for my music. Of course I LOVE forward mids.
My 6400 has quite good bass and my pair actually has more bass impact than the new 8400. Very slight improvement, but the 8400 I have has more extended bass. It's bass impact is almost non-existent. Bass may improve if you have VERY good clamping force.
The clamping force on my pair is like a 7/10. My old HD-650 was like a 9.5

 
I just wrote up a short comparison of what i'm hearing. Not a full review, but might be useful for some. Have to cut and paste that next. You probably might not agree with much of it, but who knows!
 
Overall I think IMO the 8400 is worth the upgrade, but the 6400 is not much worse. Just have to figure out which one has the signature that matches your preferences the most.

That is just so incredibly weird. With my two pairs, the 8400 fantastic bass extension like you mentioned, but there is also a pretty nice amount of bass impact as well. Bass impact and extension far surpass my 6400. When I listen to those after hearing the 8400, the thing that strike me first before the enhanced midrange is the absence of bass. Like, I need to compare it to my AD700...
 
Agree 100% there. These two are different enough, that it wouldn't make all that sense going straight for the 8400 just because it's a higher model. Both have their unique sound, and their own unique strengths. If it's possible to get both and then send one back/sell, do it! If not, I suggest anyone interested gather as much information as possible before deciding on what you think sounds best.
 
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Here are just a few comments after I listened to these headphones nearly all night. I listened to a ton of music. I even took notes since I'm a nerd I guess. It's a short comparison between the 8400 ($150) and the 6400 ($99).
 
BASS

The 6400 seems to have more bass impact than my 8400. The 8400 extends much lower though. My new 8400 has little bass impact, but the bass is all still there. The 6400 still doesn't have a ton of bass impact, but a little more than the 8400. It's not a huge difference. Drums sounds especially pathetic on the 8400. Try "W.M.A" from Pearl Jam on the 8400 to see what I mean. Despite little bass impact on the 8400, the bass on the 8400 sounds a bit better somehow. It's a lot more clear. I think the 6400 does have more mid-bass perhaps. In comparison they make my DJ100 look like an absolute bass monster and they're not even close to that! The bass on the KRKs is just presented a bit different than most headphones.

MUSICALITY

The 6400 is more engaging to me and just a lot more fun to listen to for my music. This is because the mids are more forward. The mids on the 8400 to me sound somewhat laid back. It's as if KRK wanted them to be less fatiguing for long durations. I prefer vocals on the 6400.

TREBLE

I haven't decided which is more treble happy. On paper the 8400 is and can be somewhat bothersome. On some music the treble is more fatiguing on the 6400 and on others it's the 8400. There may be some treble peak on the 8400 somewhere, so that could be why it varies. I believe the 8400 has more extended treble though overall. Could be there is a frequency on the 8400 that my ears are really sensitive to.
 
DETAIL
 
When it comes to detail the 6400 isn't far behind. On some music there is detail that can't be heard easily on the 8400 (I noticed this a TON and I was very surprised) but is there on the 6400. What's confusing is that on the 8400 with some other tracks there is clearly more detail. This is usually the case when the recording has a large soundstage. It varies between songs. On one song with the 8400 I could not hear a specific background detail until I boosted the mids by 3db, but it was so easy to hear on the 6400. It was..wind.

BIGGEST DIFFERENCE?

On the dozens of songs I listened to tonight, the biggest difference for me is that the 8400 has a better soundstage somehow. At times all the background details could be heard easier, especially echos in the recording. The size seems the same.

The absolute biggest difference is that the 8400 is a little more clear. On some songs it's impossible to tell the difference and on others it's super easy. It's the easiest to tell the difference on acoustic music with a large soundstage. We're talking like less than 3-5% more clear, if that. Again, on some (even lossless!) recordings you won't hear a difference.

The 6400 seems better for pop music, rock and female vocals. The 8400 seems to do a little better for classical, soundtracks and non bass heavy electronic music such as ambient. For my music, I prefer the 6400. Except for the bass, this comparison reminds me of the K601 vs the K702! The K601 is more like the 6400 and the K702 more like the 8400. As they say, the K702 is "technically" better, just like the 8400 is when compared to the 6400.

Nice write up! Generally agree except the bass section.
 
I will absolutely agree and confirm that the 8400 has more soundstage. The 6400 almost tends to bring "everything" more up front, so it's more like a wall of music compared the the 8400's more fan-like presentation. Every time I switched to the 6400 I kept thinking "Grado?" in the way it presents it's sound. I dunno, midrange is almost too close for me! I will continue to test.
 
I think what the 8400 reminds me most is a tamed (yet superior in many ways) DT990. The 6400 is striking me as a Grado sounding SRH940. Either one shouldn't really be compared to anything else though, because they're both special and very unique in their own ways.
 
 

 

[tdockweiler]

 
Quote:

 
 
 

That is just so incredibly weird. With my two pairs, the 8400 fantastic bass extension like you mentioned, but there is also a pretty nice amount of bass impact as well. Bass impact and extension far surpass my 6400. When I listen to those after hearing the 8400, the thing that strike me first before the enhanced midrange is the absence of bass. Like, I need to compare it to my AD700...
 
Agree 100% there. These two are different enough, that it wouldn't make all that sense going straight for the 8400 just because it's a higher model. Both have their unique sound, and their own unique strengths. If it's possible to get both and then send one back/sell, do it! If not, I suggest anyone interested gather as much information as possible before deciding on what you think sounds best.

 

 
I think between all these pairs there could be slight sound variations between them more than we think. It could be that if you have more clamping force and better bass on yours. I tested pressing them in a bit to see if the bass changes, but that doesn't work out too well

The new 8400 definitely has better bass than my old pair, but the bass impact is the same. Can't feel a thing really. It's VERY similar to how bass is presented on the K601 actually! This really doesn't bother me much.
 
I checked again before reading this to see which had more bass impact and for me it was the 6400 again. It's just so strange. I still can't get over how my DJ100 makes the KRKs look like they have ZERO bass impact. Drums just sound really really good on the DJ100. Of course my 6400 also has more mid-bass than the 8400. I'll try some different sources and see if anything changes.
 
My DJ100 sounds so much better on the Micro Amp than my E9. Right now I think my DJ100 is holding up extremely well, but may lose out when it comes to soundstage accuracy. There is an ultra tiny amount of bass bleed on the DJ100, but for having so much extra bass it's nice to have such good (and forward) mids. From my Micro amp the DJ100 seems to have more treble than my 6400.
 
I think it's safe to say that the 8400 is the more relaxed pair for me when it comes to the bass and mids. I think the treble may have smoothed out a bit after listening and burning them in for awhile. When I switch from the 6400 to the 8400 the sound feels a bit more distant, which is what some may treble. I prefer the in your face type of sound I guess. I nearly always prefer forward sounding mids. You'd think I'd be a huge Grado fan by now, but not yet!
 
Biggest surprise is that the DJ100 can compete extremely well with the KRKs when it comes to detail. Who would have thought that...It may be a slight step down in sound clarity with some music, but not by much.
 
BTW if I could compare my 8400 to ANY headphone, it sounds closest to the K702, but with smoother treble and more bass extension and detail

The 8400 has very slightly more forward mids though compared to the K702 only though.
I know this is seriously weird. The new 8400 sounds similar to the old one, but has slightly better bass and the treble is a lot better.

 
 

 

[zyzyx]

Thanks for the reviews, guys.
 
Katun - Am I correct in assuming that you listened to the 6400s with the stock pads?
 
tdockweiler - Did the change in pads influence sound - particularly bass - on the 6400s, as far you can recall?
 
Not critical questions for me, as I should be receiving the memory foam pads for the 6400 on Tuesday, but I am curious as to how much of these sound perceptions are due to subjective (individual ears) or uncontrollable factors (manufacturing variance b/w headphones of the same model)...versus variables such as different pads.

 

[tdockweiler]

When changing 6400 pads between the stock and memory foam pads I didn't notice any change in sound at all. Based on my experience changing to different pads can usually mess with the sound too much, but not here luckily! I might be able to do some more A/B comparisons, but it's annoying to change the pads.
 
EDIT: I just did a test between the stock and memory foam pads of the 6400. Didn't notice any changes in the bass at all. It felt like the stock pads made them a bit brighter, but it's probably my imagination. It's really hard to want to go back to those stock pads now with these memory foam pads.
Quote:

Thanks for the reviews, guys.
 
Katun - Am I correct in assuming that you listened to the 6400s with the stock pads?
 
tdockweiler - Did the change in pads influence sound - particularly bass - on the 6400s, as far you can recall?
 
Not critical questions for me, as I should be receiving the memory foam pads for the 6400 on Tuesday, but I am curious as to how much of these sound perceptions are due to subjective (individual ears) or uncontrollable factors (manufacturing variance b/w headphones of the same model)...versus variables such as different pads.

 

 

[Katun]

 
 
 
Quote:

I think between all these pairs there could be slight sound variations between them more than we think. It could be that if you have more clamping force and better bass on yours. I tested pressing them in a bit to see if the bass changes, but that doesn't work out too well

The new 8400 definitely has better bass than my old pair, but the bass impact is the same. Can't feel a thing really. It's VERY similar to how bass is presented on the K601 actually! This really doesn't bother me much.
 
I checked again before reading this to see which had more bass impact and for me it was the 6400 again. It's just so strange. I still can't get over how my DJ100 makes the KRKs look like they have ZERO bass impact. Drums just sound really really good on the DJ100. Of course my 6400 also has more mid-bass than the 8400. I'll try some different sources and see if anything changes.
 
My DJ100 sounds so much better on the Micro Amp than my E9. Right now I think my DJ100 is holding up extremely well, but may lose out when it comes to soundstage accuracy. There is an ultra tiny amount of bass bleed on the DJ100, but for having so much extra bass it's nice to have such good (and forward) mids. From my Micro amp the DJ100 seems to have more treble than my 6400.
 
I think it's safe to say that the 8400 is the more relaxed pair for me when it comes to the bass and mids. I think the treble may have smoothed out a bit after listening and burning them in for awhile. When I switch from the 6400 to the 8400 the sound feels a bit more distant, which is what some may treble. I prefer the in your face type of sound I guess. (1)I nearly always prefer forward sounding mids. You'd think I'd be a huge Grado fan by now, but not yet!
 
Biggest surprise is that the DJ100 can compete extremely well with the KRKs when it comes to detail. Who would have thought that...It may be a slight step down in sound clarity with some music, but not by much.
 
(2)BTW if I could compare my 8400 to ANY headphone, it sounds closest to the K702, but with smoother treble and more bass extension and detail.
 
The 8400 has very slightly more forward mids though compared to the K702 only though.
I know this is seriously weird. The new 8400 sounds similar to the old one, but has slightly better bass and the treble is a lot better.

Well, I've actually had a cold for the past couple days, and today it's *really* effecting my hearing. Both of these now sound painfully bright, which I know is not the case. I'll have to continue my listening session later this week, unfortunately.
 
(1) Okay. You have got to try out the SRH940 then. Comfort or not, I absolutely think you'd love them. I'm talking, "Scoot over DJ100, your replacement has arrived". I'm kinda a wuss when it comes to comfort, so you may not even find them that bad.
 
(2) If I hadn't tried the 8400 before, and you told me that, I would pick them up in an instant. That's exactly what I'd want in a sound.
 
See, maybe the bass is effected by the two different pads? The memory foam has a better seal than the stock, so maybe that is why we are hearing differently. Then again, probably not THAT much of a difference regarding both pads. Who knows?
 
I actually did a comparison between the AD700 and 6400 just barely. Yes, I'm sick, but I'm not judging treble (bass doesn't seem to be effected). Anyway, the 6400 does indeed have more bass, but we are talking small amounts here. The AD700 doesn't have too good of extension and seems to bottom out two early, and impact seems rather light and quick. The 6400 extends deeper (although kinda hard to hear because the bass in general seems subdued against the rest of the sound) and also has a tad more impact and flesh to it. Again, weird? Probably.
 
Quote:

Thanks for the reviews, guys.
 
Katun - Am I correct in assuming that you listened to the 6400s with the stock pads?
 
tdockweiler - Did the change in pads influence sound - particularly bass - on the 6400s, as far you can recall?
 
Not critical questions for me, as I should be receiving the memory foam pads for the 6400 on Tuesday, but I am curious as to how much of these sound perceptions are due to subjective (individual ears) or uncontrollable factors (manufacturing variance b/w headphones of the same model)...versus variables such as different pads.

Correct. Stock pads.
 
Easily all 3. With subjective hearing reigning supreme.
 

 

[kiteki]

 
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I know that I do not have a lot of post but I like lurking more for some reason. I was interested in these since your review which is great by the way. I have a question. You stated that many genres are compatible with the KRK KNS-6400. My question is would the Vocaloids genre fit with these? I've been searching the forums for many headphones relating to Vocaloids. I have the Meelectronics M6-BK so these would be my first or second headphones I would actually own. Well I listen to hip hop/rap, jpop, kpop, and anime op/ed so I wonder if these would be compatible as well. Thanks for listening to my reply or answering my question in later post(s).

The Hifiman RE0 or RE-Zero is the only headphone suitable for Vocaloids.
 
 

 

[jant71]

Nice comparisons! Thanks to you guys for all the good impressions so far. Probably just stick with my 6400's since for the mids and up front sound especially since they are a good match with my EX600 as far as closer presentation & mids, overall sound signature, and engaging factor. I do want a shorter cable though. May just buy the 1.5M KRK cable for $10 but I will research some other cables as well as long as they aren't over $50.
 
 

 

[tdockweiler]

Just did some non-competitive gaming with both pairs today for a few hours. I think it's safe to say that the 6400 is one of my favorites that's closed for gaming. Tons of detail, clear sound and those slightly forward mids. The 8400 was kind of a little annoyance due to the mids being a little too more distant. Overall I don't think the 6400's mids are super forward. They're less forward than the DJ100 and HD-598 for sure. At least the HD-598 with the mogami cable. Not sure about stock. I generally hate closed headphones for gaming, but this has a soundstage that's good enough to make it worth using. For gaming, the 6400 seems to have a balance of being good for competitive gaming and then just for fun. Has enough bass for most things.
 
It's weird taking off the 6400 and putting on my K601 for games. It's like.."Where'd the mids go?". The K601 has good mids, but the 6400's mids are even more forward than the K601. I guess the mids on the K601 aren't as forward sounding as I once thought! I could probably listen to the K601 all day and not have my ears get tired. Despite that it doesn't bore me much like my old HD-600 did.
 
I also figured out why I felt the 8400 had more treble. It was my amp. On my E9 it's noticeably less fatiguing when it comes to the treble. On the Micro amp there is a little more treble for sure. Not sure where it's boosting it, but it's not too bad. The KRKs with the E9 is nowhere near as good compared to the Micro amp. It loves the KRKs. The mids seem a tad better out of my Micro amp compared to the E9. Strangely this was the case with both amps when I used the K702! The K702 had fuller and more forward mids on a better amp. On the E9 they often felt recessed and a little thin in comparison. Right now when well amped, I could never say the 6400 seems to be lacking any treble that's for sure!

 

[soundstige]

Your comments made me buy a pair (6400) to try out tdockweiler. The way you described them sounded exactly like what I want a $100 pair of headphones to sound like, I'm very excited

 

[tdockweiler]

Let us know how you like them! If you do, they're worth upgrading with the 8400's memory foam pads..although you may not need to. I stretched my pads a little on the first day. To me, these are one of the most comfortable headphones there is when memory foam pads are used. Even without them they're comfortable. OK, a step behind the K601, but pretty close!
I really can't get over how good these sound for just $100. Especially how clear the sound is. Certainly no bass monster, but has more than enough bass for me. I think there is only one headphone in existence where I felt it didn't have enough bass...it was the AD700!
 
Quote:

Your comments made me buy a pair (6400) to try out tdockweiler. The way you described them sounded exactly like what I want a $100 pair of headphones to sound like, I'm very excited

 

 

[FlySweep]

The Hifiman RE0 or RE-Zero is the only headphone suitable for Vocaloids.

Speaking of the RE0.. I get the sense the 8400 is the RE0 in headphone form, in terms of sound.. ??

 

[tdockweiler]

Quote:

Speaking of the RE0.. I get the sense the 8400 is the RE0 in headphone form, in terms of sound.. ??

No, not at all to me. The RE0 actually almost makes the 8400 look bass heavy in comparison

The mids on the 8400 are more forward I believe. I do remember the RE0 did seem to have a lot of detail, but I don't remember it all that well.
The RE0 is one of my most hated IEMs unfortunately. Everyone else seems to love it though!
 
To me, I clearly remember the RE0 sounding more like the AD700, but with a smaller soundstage of course.
 

 

[kiteki]

So, care to elaborate why it's your most hated IEM?  Or are you just gonna be like Katun "it sounds weird" @Z1000

 

[tdockweiler]

Probably because it doesn't match my preferences? Or that I have used about 4 IEMs in my entire life and prefer headphones?
For me the RE0 has what felt like non-existent bass. Pretty sure I mentioned this above. I had one of the very early pairs.
Wow, I don't know what to say about your sarcastic comments or if this is even a serious question. I doubt it.
Feel free to check my old threads for more. I haven't owned them in probably 1 1/2 years maybe?
 
People can't like a headphone now without giving a 10 page review?
I've seen Katun's comments on the Z1000 and it's hardly fair to say he just thinks it "sounds weird".
Even if so, why do you care? It's his money.
 
I wonder how different the ZX700 is to the 1000. The ZX700 sounds a bit "off" too and not accurate despite being a "Studio Monitor".
I wonder if they have any similarities. Probably not.
Quote:

So, care to elaborate why it's your most hated IEM?  Or are you just gonna be like Katun "it sounds weird" @Z1000

 

 

[Katun]

Quote:

So, care to elaborate why it's your most hated IEM?  Or are you just gonna be like Katun "it sounds weird" @Z1000

I said a bit more than just, "It sounds weird". But, I'd love to tell you all the reasons why it sounds "weird" if you'd like.
Sneak preview: Slightly flabby bass, very distant and veiled midrange, and bright treble that doesn't extend. And a messed up tonality.