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KRK Systems KNS 6400

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MSRP $129.00
This product is no longer available at HeadRoom.

The KRK KNS 6400 are flying under the radar --  but not for long. Headphone lovers worldwide who've spent ear time with the KNS 6400 have been shocked and awed at the acoustic clarity and dynamic extension of these cans; some require full resuscitation after they discover the KNS 6400 budget-friendly price and compare it to their high-end audiophile cans. Amazing sonic bang for the buck.

Here's a groovy HeadRoom blog post on the KRK Systems line of headphones.


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Product Features:

  • Very impressive sound quality at this price
  • Sealed-back earcup design for isolation and listening privacy
  • Detachable /replaceable headphone cord
  • Rated up to -26 dB ambient noise blocking ability

What's In The Box:

  • Protective storage/ travel bag
  • Anti-microbial KRK cleaning cloth
  • 1/4" stereo plug adapter
  • Owner's manual / product guide


The KRK Systems KNS 6400 headphones are a great way to get into serious professional-caliber monitoring and top-shelf personal listening without having to break out some serious moolah. Although not widely heralded (yet!) outside 'in-the-know' pro audio circles, headphone lovers everywhere are in for a wonderful sonic treat once they hear the simple, clear, and balanced tonal presentation delivered by the KRK KNS 6400. At this magic $99 price, there is frankly not much else we've heard that out-performs the studio-level accuracy and low-frequency extension of this can. Copper-clad aluminum wire voice coils and neodymium 40mm driver arrays reproduce the exact signal from your audio source with no coloration or distortion added to the mix. Rated impedance of 36 Ohms allows for effective use directly from mobile players and laptop computers but add a headphone amp to the equation for more acoustic suppleness and soundstage imaging depth. Expect excellent isolation from the KNS 6400 closed-back earcups for superb listening privacy in any setting and zero leakage into the mic during recording or vocal work. Highly recommended, well-priced headphone find for recordists, mixers, DJs and personal monitoring of all music genres.

The KRK Systems KNS 6400 have a mid-sized circumaural sealed-back construction that allows the earpads to rest comfortably around the outer part of the earlobes on most wearers. The fully adjustable, tough-built sprung-steel headband design provides a low-pressure, non-clamping ergonomic fit that is both secure on the head yet comfy even during those extra-intense, extra-long listening sessions. Fully replaceable earpads and headband cushions make it easy to maintain these headphones in tip-top shape as you own them through the years. The detachable / replaceable headphone cord is another big plus for product durability and locks into the headphones using a beefy connector sans any sound quality degradation.


  • Connector Type: 1/8
  • Weight: 202 grams w/o cable
  • THD+N: < 0.1%
  • Isolation: -12dB ~ -18dB
  • Detachable Cable: No
  • Impedance @ 1kHz: 36 Ohms
  • Cord Length: 8.2 ft.
  • Cord Type: Straight Left-Side
  • Coupler Size: Large
  • Driver Type: Dynamic
  • Ear Coupler Type: Full-Size
  • Headphone Type: Full Size
  • Acoustic Seal: Closed
  • Manufacturer Warranty: 1 Year
  • Sensitivity: 95dB

Reviews At A Glance
3 Reviews
1 Reviews

Average Rating 
(Showing 3 of 4 reviews)

Posted by Rillion from Maryland on 2011-11-13

Recommend Product: Yes
Pros: Great sound, great price
Cons: may need an amp with some portable players

Update: Nov. 28, 2012

Of the 4 sealed headphones I own, these are still my favorite.

I made a big deal in the review below about these headphones not reproducing echo and reverb quite as well as other headphones. I've since figured out that this is just because these headphones have a somewhat "warm" tilt to their frequency response to my ears. This is fixed by simply cutting the Bass by 2.5 dB and boosting the Treble by 2.5 dB with Rockbox. Rather than adjusting Bass/Treble, the same thing can be achieved with the parametric EQ with Low Shelf freq = 200 Hz, Q = 0.5, Gain = -2.5 dB, High Shelf freq = 3500 Hz, Q = 0.5, Gain = 2.5 . Since measuring my hearing with a variety of headphones and speakers, I don't use the other EQ I mentioned below anymore. The KNS 6400 requires very little tweaking to sound natural, at least to me. It truly deserves the designation "reference headphone."

Update March 2, 2012:

In the review below, I implied that adding a headphone amp while listening to these from my Clip+ player improves the sound. The KNS6400 is driven plenty loud (for me anyway) without the amp and I think during my original listening tests that I didn't have the volume quite matched between my "with amp" and "without amp" comparisons. I recently matched the volumes by measuring the output voltages from a test tone and making a slight correction for the output impedance I measured on my Clip+ (0.8 ohm) and E5 amp (0.3 ohm). After matching volumes, bass seems to have more detail through the amp, but frankly I would be hard-pressed to tell the difference in blind listening.

I've owned my KNS6400 for about 4 months now. When I'm in the mood for big 'phones I oscillate between favoring these and my AD700 (mentioned below). The only generalization I can make is that for me the AD700 is superior for classical music. This does not mean that the KNS6400 is bad with classical, just that the AD700 is exceptionally well suited for classical with its silky smooth mid-range and amazing imaging: qualities that work very well for instruments played in a music hall that are not electronically driven That said, the KNS6400 has excellent instrument and voice separation and a well-extended bass. For some reason, echo and reverb just doesn't sound right on the KNS6400 but this usually doesn't matter with studio recordings. This just might be something that sounds more natural with an open design like the AD700.

Below is my original review unaltered.

First off, I was a little worried from the HeadRoom frequency response
thumbnail graph that there would be an audible imbalance between the channels
in the sub-bass. My left ear is already more sensitive to bass. Thankfully,
when I received my KNS 6400 headphones I found that there was no noticeable

I did some side-by-side sound comparisons between the KNS6400 and my Audio
Technica AD700 and Phiaton PS320. I have two Sansa Clip+ portable music
players so I could match the volume levels. Such comparisons are rather
time-consuming, so I focused on two music tracks: (1) Moonlight Sonata, Adagio
sostenuto, on "Favorite Beethoven Sonatas" performed by Horowitz and (2)
Dream Baby on "The All-Time Greatest Hits of Roy Orbison". For both pieces of
music the sound quality of the KNS6400 was only on par with the other two
headphones with the use of a headphone amp -- the cheapo Fiio E5 (I haven't
tried other amps). These are all very good sounding headphones to my ears.
Without the amp, the sustained piano notes (sostenuto) on Moonlight Sonata
sounded shortened in duration through the KNS6400. With Dream Baby, the
causes of the differences were harder to put my finger on but clearly impacted
music enjoyment. The frequency response of the KNS6400 and PS320 are very
similar, but the KNS6400 has stronger deep bass -- the double-bass at the
start of Dream Baby sounds slightly exaggerated to me with the KNS6400.

In terms of build, the KNS6400 is mostly made of thick plastic with some metal
screws and a metal strip inside the head band. The cover over the padding
(ear and band) is paper thin, but the pads are replaceable. The cable is
replaceable too. The cable is stiff enough to transmit some distracting noise
to the ear cup if the cable is knocked around or dragged. The headphones
muffle outside noise fairly well. The ear cups rotate to allow the 'phones to
lay flat. So far, they have weathered three 13 hour road trips in a suitcase
without any sign of wear.

These are sealed headphones so they can get uncomfortably warm. In a 68
degree F room, they remain very comfortable for at least the duration of a 40
minute album. At 75 degrees F, I need to take a break after 15 minutes. I
suspect that I'm more sensitive to heating than most, since I haven't seen
this mentioned with other reviews.

These headphones are a fantastic bargain.

These are fairly neutral sounding headphones, but if you want an even more
neutral sound, you might try these Rockbox parametric equalizer settings: Peak
1: 70 Hz, Q=3.1, +3.5 dB, Peak 2: 100 Hz, Q=1.0, -2.0 dB; Peak 3: 250 Hz,
Q=0.8, -6.0 dB.

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6 out of 6 people found this review helpful. Did you?

Great studio headphones, so I returned them
Posted by Magnite from Ann Arbor, MI on 2011-07-01

Recommend Product: Yes
Pros: Comfy, great build quality, excellent clarity
Cons: Not fun for personal use; balanced but low bass

These headphones are exactly what they claim to be: a great set of studio monitoring headphones.

I returned them because using them to have fun with my own personal music was disappointing. They are so clear and precise that I get no real impact from a song. It seems to take each part of a song (e.g. bass, vocals, guitar) and separate it from the other parts. I can respect their overall build quality, amazing clarity, and balanced sound. They seem to do what they claim: being an amazing studio headphone. But, they are NOT very fun to listen to at all, and these would've been my personal listening headphones from my iPod. It seems like:

*There's not enough bass (very balanced, but not enough to really get me pumped about my music). They just don't punch enough and I don't receive the impact from my music that I would with other sets of headphones I've used (see below).
*They're kind of "too clear". The different parts of the song are almost separated from each other. It's almost like when you use them, you listen to the different parts instead of the song as a whole. The may be good for the studio, but it's bad for me.
*Seems way too analytical (i.e. soulless) and not very good for having lots of fun with my music.

BUT, I would highly recommend them to someone who needs a headphone with amazing clarity, precision, and excellent construction built for studio work.

Sound Quality
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9 out of 12 people found this review helpful. Did you?

Clean, Analytical, Balanced Sound... Monitors for your head
Posted by dnebab2890 from San Francisco, CA on 2011-06-01

Recommend Product: Yes
Pros: Comfortable, User Replaceable Parts, Professional Sound, Wearable for Hours
Cons: None

Purchased these as I've recently started learning audio editing (aspiring audio engineer) and I was looking for cans that will give me accurate sound at a decent price. Also using these for listening to music from an unamped Creative Labs X-fi2 media player.

Analytical, Clean, Detailed Sound. Great for critical sound work. There are quite a few other potentials at this price-point with similar sound, but these take the cake due to replaceable parts, down to the cord. Most phones had a non-detachable chord. Balanced lows, mids, and highs through-out. Great for listening to music as well if you prefer hearing the "as it was mastered" version of your music.
I'm noticing details in my music that I didn't find with other phones, even my all time favorite Sennheiser PX100 (original) seemed just "okay" compared to these.

I find these a "headphone version" of KRK's speaker monitors. Great for late-night work, or when you don't want to be disturbed, or disturb others. Great to take your editing on the go via laptop.

These are built to last, very sturdy and handles heavy use well. Again, user-replaceable parts definitely helps here. Switch out the chord if needed (KRK sells different sizes, included straight cables and coiled cables.) The higher model (KNS-8400) has memory foam ear-pads, which can be used on the 6400 as well, for added comfort to an already comfortable set of cans.

***Isolation & Misc***
These aren't the flashiest phones out there, but they sure sound great. Isolation is great, making listening to music, mixing, and monitoring in moderately noisy environments a breeze. Doing vocal work? These don't leak into the mic due to great sealed design.

- A definite buy.
- Clean, Detailed Sound.
- Great headphones from a great audio company

Sound Quality
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12 out of 12 people found this review helpful. Did you?

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