Review: KEF M400 headphones

A brand synonymous with excellent audio, KEF is at it again with a pair of on-ear headphones that aim to bring audio to a compact and fashionable package. Does it succeed?

Features and performance

There are plenty of speaker brands out there, but not all of them enter the world of headphones, and some take their time before releasing any old thing, or any new thing.

English loudspeaker manufacturer KEF definitely sits in that last category, because while it has been around since the 60s making speakers, it wasn’t until a few years ago that it decided to get into portable sound.

In that time, we’ve certainly had our fair share of the headphones KEF makes, and each has offered a very clear and distinct representation of sound, much like the KEF speakers we’ve experienced.

But not everyone is necessarily going to be after the same type of sound, so with that in mind, KEF has built a slightly different pair made for the modern listener who may not want a large pair of cans or a very big pair of in-earphones.


Rather, the KEF M400 feels like the focus is on the casual listener who may be after clarity from their sound, but not necessarily something that distances them complete from the outside world.

Opening up the M400 box, that feeling starts to become justified because the M400 feels like it’s a smallish headphone, design to sit on the ears with a plush leather encased memory foam that doesn’t press too hard against the fleshy bits we call “ears”.


Out of the box, we already expect the one included cable to be of the Apple MFi variety or “Made for iPhone” for those people at home tired of initialisms, and we’re proven right, so if you have an Android phone or pretty much

A case is included for your benefit, and while it’s small, it has been made this way due to the fact that the M400 cans are collapsible.


This is because the hinges are built in such a way where you can fold the cans in on themselves, flipping inwards for a truly compact design, the likes of which we’ve seen before but still results in a design that you can take with you quite easily.

For now, though, we don’t want them collapsed. Rather, we want them expanded and on our ears, because it’s time to take the KEF M400 headphones for a spin.


On the ears, you find the headphones sit in the supra-aural category, and that is to say they sit on the ears. These won’t encompass your ears entirely, and there’s a plush leather with foam backing to keep your ears comfortable throughout the music experience.

A metal band and design means the M400 headphones can sit firmly on your head, and they don’t even provide too harsh a squeeze, meaning you can comfortably listen for hours if desired.


As usual, we get stuck into the music test by using the GadgetGuy 2016 Sound Test, and electronic starts our test off, treating us to detail across all the spectrums — highs, mids, lows — though it feels noticeably punchier in the highs and lows, with the mid a touch subdued.

Tracks from both Imogen Heap and Demi Lovato in our test list seemed skewed towards a brighter sound, and while it was detailed, it was definitely a little more punchy than we were used to.


Shifting gears a little into the more soulful side of life, Daft Punk’s “Get Lucky” and Mark Ronson’s “Uptown Funk” offer a lush and rounded bottom end with vocals clearly on top, while the mids for percussion are pulled back in comparison. It’s not a bad sound, either, just one that is clearly supposed to be punchy and with a thwack, as if it is made for music of the youth.

That makes us super curious as to how the KEF M400 will sound with lighter music, such as the jazz and classical tracks that will rock up next.

First, though, there’s pop and rock, and Sara Bareilles’ “Brave” is super bright, the highs of Sara’s voice shining through first and foremost with the punch of the bottom end, highlighting what we’re hearing with other music styles.

We do need to note, the mids are super detracted, and the M400 are definitely not shallow cans, but the structure appears aimed at a brighter and top-heavy sound.


And then rock surprises us, with a full sound as Radiohead’s “Exit Music” stretches across the spectrums, and Nirvana’s “Come As You Are” delivers a meaty bottom end with Cobain’s vocals ringing out atop.

Muse raises this up a bit, with strength in the lows and a solid amount of grunt, while The Who offers a surprising amount of detail for the size of the cans, recreating an experience like that of the M200.

Rock has no problem with these cans, but the bottom end is still the most powerful section here in most of these tracks, leading the highs and mids.

That gels with what we’re feeling, solid top and bottom, with decent mids, and over into classical and jazz the same feeling emerges. Given the bottom end is less punchy in these styles, we found the cans much brighter, though the performance rarely lets up.


Outside of the sound, the durability seems quite well tested, with the aluminium frame delivering a solid strength from the headphone frame and fairly tight hinges when you fold the cans up.

Weeks in, we’re not feeling like we’ll lose the hinges to time, which is something we felt on Sony’s otherwise excellent h.ear on MRD-100AAP headphones.


The leather band helps to protect this metal frame, which will no doubt help durability long term, but the paint job doesn’t get the same feeling, with the exterior of the cans picking up a few scratches in no time, and that was without even trying.

You’re definitely going to want to use the headphone case here to keep it in good nick, though to be honest, we did that and we still picked up on the odd scratch. Perhaps you just can’t keep a metallic paint job from eventually wearing in.



KEF may be known for its speakers, but the company has a pretty good understanding of headphones too, evident from the previous efforts.

We’ve loved the M500 on-ears as well as the M200 in-ears, and the latest set are great again, albeit a different kind of great. Essentially, KEF has imbued them with a more vibrant and bright sound than we typically see, because while the warmth has been scaled back, they are deliciously dynamic.


Value for money
Ease of Use
Reader Rating1 Vote
Bright, detailed sound; Portable with collapsible design; Sturdy build; Finally, a KEF cable that doesn’t use the 2.5mm jack;
Not as warm as M500 headphones; Headband is a little tight; Remote cable will only properly work with iOS devices (MFi); Paint job deteriorates surprisingly quickly;