Pros: Lightweight, Comfortable, Easy to Drive, Balanced midrange
Cons: Extension could be better
As per standard, I will give a bit of a background to premise this review. I do this before all of my reviews just to give the reader an idea of my experiences. This allows the potential consumer to best judge my opinions and ultimately decide what kind of bearing my words have with them. My reviews aim to express my thoughts with the main intention being to arm the reader with the knowledge to make the best purchasing decisions. Knowledge is power, and I say power should go to the consumer in any market!
I come from a family of audio hobbyists/philes/enthusiasts/whatever. Hi-fi has been part of my experience from the time of a child, and thus my standards for audio reproduction are naturally higher than that of your average individual or consumer. I’m not making the “golden ears” argument, I am saying I have been around many different niches and types of hi-fi reproduction and my ears have received some training in the process. My first exposure involved home fidelity, but I first started becoming adventurous in the car audio department when my teen years hit (naturally). I found myself buying, selling, demoing, and modding consistently until I eventually completed a final project of building an entire audio system from the battery up. I haven’t had to touch it for years, and probably won’t for a long time. From car audio I moved back into the home theater/hifi scene and did some projects of my own, once again. I have recently found my audio nirvana in the home, and don’t plan to touch that for awhile either after much testing/tweaking. Naturally, my next move was the headphone world. I’m currently diving into cans, learning as much as I can until I find my “heaven” in this realm too. It is helpful reviews that help pave the way for those who want that ultimate experience, so I plan to contribute and pay back in the process. I hope you find the following review of the KRK KNS-8400 helpful.
Comfort: The fit of these headphones is certainly above average to me. It was one of the first things I noticed when swapping from other headphones of similar class like the Shure SRH-840, SRH-440, Sennheiser HD-25 I-II, HD280, HD380, HD448… even against higher tier models like the SRH-940, Beyer DT-770, Senn HD-650, CharterOak SP-1. These headphones are comfortable overall because of the soft memory pad filled leather-esque pads utilized on both the headband and ear pads. Even with this super padding, they are very light. The clamping force is enough to be considered secure, but at the same time the soft pads do not apply much force around the ear. I usually rate comfort on a secure fit to a loose pillow fit spectrum, and let the reader judge how “good” the comfort is based on what they prefer. These fall in the middle of this spectrum somewhere; they have enough clamping force for you to move your head around without fear of slipping but do not have zero pressure at the ears. I really find the balance fit to be quite nice, and certainly one of the nicer ergonomic designs around. They won’t be as comfy to me as my SP-1 or HD-448, but they certainly will fit more securely which is almost a must for a portable. I feel like whether you’re a pillow fit or secure fit person, these can’t let you down in the very least. They’re just fine for multihour listening sessions and actually don’t warm your ears up a ton for being a closed back model. Solid job, KRK.
Durability: Since I feel like these fit best in the portable niche, I’m force to elicit a higher standard. The durability is fine. They certainly won’t fall apart in your hands or crumble in your backpack, but they might have a weak point or two. Anytime there is a swivel joint, a chance of weakness is introduced. I’ve seen swivel models implemented in poor fashion and in nearly indestructible fashion. These KRKs fall somewhere in the middle again. The swivel joint in the headband that allow them to fold flat is pretty solid and protected in all direction. The screw isn’t visibly exposed from any angle, which is a good thing. It also doesn’t utilize a spring to snap back into place like I’ve seen before, which could be a good thing from a durability standpoint, as it is well known that springs can wear out. The joints at the ear cups that allow the cups to tilt would be more prone to breaking that the aforementioned joints. Honestly though, the only way I could see that happening is if there was a downward pressure pushing the cup further from its yielding point and causing it to snap (I could see this potentially happening at the bottom of a backpack, for instance). The cable seems durable, yet still small enough for convenient portable use. It is indeed detachable, although the locking design isn’t the slickest. Once it is locked in I don’t think it is going anywhere as it utilizes a turn-to-lock system, AFTER being snapped into place (semi-forcefully too, I should add). Could this mechanism wear out? It wouldn’t particularly surprise me either way. I’m probably splitting hairs in this section, but I think it is well to consider everything. On the plus side, the headband is reinforced with lightweight metal and a plastic beam, and the pads are mounted really well on the headband. It even seems as though this may be replaceable by unscrewing a panel and swapping. I’ve certainly seen less durable portables, so I think these will hold up just fine through the battles of travel with just a little care and caution. Don’t be stupid and they shouldn’t break.
Sound Quality: The comfort and durability may be the bread, but we all know it is what is in between that makes or breaks the sandwich – even if the bread is essential. Just so you can get an idea just what kind of sandwich this is, I will break the sound up into the three logical categories of high, mids, and lows. I will comment on each, likely referencing each within my comments to help you get an idea of how it all blends together. I spend a lot of time before writing this section of the review, and it is always done separately from the rest of the review. I listen to many tracks from many different genres and report my SUM experience here. If you want an idea of the types of tracks I used, feel free to PM me or something and I can tell you some of my favorite evaluation tracks. I will preface this section of the review by reminding you of my background in audio (see intro if you wish). My honesty can come off a bit harsh sometimes, but I will attempt to help you understand my subjective experience to the best of my language abilities.
Highs: This certainly isn’t an emphasized aspect of the spectrum. Cymbals in rock tracks that are notorious for getting out of control seem reasonably sustained. The level of control in the highs is quite nice actually, and it is my guess that this control is what makes the sound of these headphones not so fatiguing. Cymbals seem to have more of a “sss” sound rather than a “shhhapp” or “shhhh” sound, if that makes any sense or is helpful at all. I guess the highs sound thin, in a sense… but not in a negative way necessarily. While this does wonders for avoiding a fatiguing nature, it also means that high string notes are a little duller than I prefer. Detail retrievable is a bit hindered in the highs because of this. The sparkle that should be there on certain tracks can be a little laid back (for sparkle that resides in the highs, at least). I will say that I do find the highs (8-10kHz and up) to be quite linear in sound, even if masked a little bit by their laid back nature… and maybe even a bit rolled off. The roll off is actually a bit disappointing considering their potential as a monitor due to this linear presentation in the highs. If someone came up to me and said “the highs are a little veiled in this headphone” I couldn’t really disagree with them. I don’t think the highs are veiled in the sense that they are dark, I think they are veiled in the sense that they lack some sparkle and detail (not suggesting sparkle = detail). Listening for details and separation is always more challenging in the highs anyways, so this potential handicap really doesn’t take away from the sound of these headphones too much… I just don’t think they are the best for doing tracking in the highs. If that’s something you need, look elsewhere because these are not honest/revealing enough up top.
Mids: When compared to the highs you could say the mids are emphasized, but I certainly don’t think there are emphases within the mids themselves. It is common to hear a midbass emphasis in a closed set of headphones just because of the inherent design of the sealed enclosure. These do a good job at taming that potential by producing a pretty neutral midrange. I know it seems like everyone and their mother is reporting this and that as “flat” recently, but I honestly think the mids here sound quite unemphasized and neutral. From my experience neutral presentations are much more rare in the headphone world than in the loudspeaker world, and this makes sense because of the design. Compared to the loudspeakers I’ve had the pleasure of spending decent time with that are neutral sounding, these KRKs do sound neutral to me in the midrange. I don’t get a sense of “cold” or “warm”, and I don’t notice any part of the midrange shouting at me for attention. This makes it easy for me to choose part of the midrange sound and focus on it, and even easier for switching from one instrument or sound to the other within the midrange to focus on. To me, this is indicative of little to no emphasis on any particular section within the mids and therefore a subjectively perceived flat sound in the mids. Notice my careful language here. I find the highs a bit recessed, so I can’t say the overall sound is flat, but I can say the mids do sound neutral. The flatter response certainly favors detail retrieval in this part of the spectrum when you’re looking for it. I don’t find anything to jump out at me, but I do find it easy to find any part of the music in the midrange when needed. This seems super useful for monitoring/tracking purposes. The mids are true, and I really like that about this set.
Lows: Bass always suffers it seems like. It is like the sauce, you better pick the right one to compliment the rest of the sandwich or it could ruin it all. Getting a sauce right adds texture to the sandwich. A dry sandwich is better than one with the wrong sauce, yet everyone generally sauces their sandwich because without it, it just isn’t the same. A well liked, but conservative sauce was used here… something far from mustard or hot sauce and closer to something like mayo or bbq. I have hardly any complaints about the bass. My only real complaint is that is it unspectacular, which is kind of a cheap shot in itself. The bass is really shed in a similar light as the mids are to me. There is no midbass punch, no grumble, and no real low growl. The bass lacks significant in-class emphasis. Just like the highs though, I wish the extension was just a little better. The bass is a pretty linear to my ears but once it gets to the 60Hz and below region it seems to start rolling off a bit. Usually the trade off in bass is impact versus texture, and once again I find the KRKs to fall somewhere in the middle. The impact isn’t bland, and the texture isn’t muddy. I can hear tonal changes in the bass fairly coherently, and I hear some punch when the track calls for it. The bass isn’t as fast as I’d like; the recovery could certainly be better. That being said, I don’t think the speed in the bass is bad… just average. A good fusion band like Chicago which utilizes electronic and string bass will show you what I am talking about. The slick string bass responds pretty well, but isn’t as swift as it could be. Usually bass that can keep up with strings like that lack some impact properties, so I guess that is just one extreme example of what I mean when I say bass texture. Overall, you put this sauce on my sandwich and I’ll rarely complain. I won’t go home thinking it was the best sandwich I’ve had either.
Additional Notes: The isolation is just fine. Nothing to ride home about but it won’t disappoint (I feel like this sentence has been the theme of this review). It appears that parts like the pads, headpad, and cable are all replaceable and purchasable. The headphones are easy to drive, although modestly enjoy even a simple amplifier like the FiiO e7. It comes with a threaded 6.3mm jack that is removable to be a 3.5mm mini. The headphones do fold flat, but do not come with a hardcase but rather a drawstring pouch for portable storage. These also come with a removable inline volume control, which is cool if you’re listening out of a shared source and the other user isn’t using a volume you prefer, or for a fast kill switch.
Nutshell: These headphones lack a glaring weakness sonically and are ergonomically very friendly. The asking price is quite reasonable (I got mine for 120, and it was going at that price in many places at the time of this review). I think these headphones would be most useful for tracking/monitoring in the midranges. In fact, these wouldn’t do horribly as a monitor at all considering their fairly neutral overall presentation and their especially neutral midrange. For music listening purposes, I feel like these are a great well rounded set. I don’t they will be spectacular in any specific genre, but I also don’t think they could disappoint either, and that versatility has to mean something. This set is like a turkey melt; a safe go-to sandwich that is hard to mess up, guaranteed to taste fine no matter the time of day. It almost seems like the perfect entry level headphone for a new comer to hi-fi, yet could be easily enjoyed by the audio veteran. Kudos KRK, for a great value and well-rounded “plug and play” set!