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KEF M400

 & Tim Gideon Contributing Editor, Audio

Our team tests, rates, and reviews more than 1,500 products each year to help you make better buying decisions and get more from technology.

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KEF M400 - KEF M400
4.0 Excellent

The Bottom Line

A little light on accessories for the price, KEF's M400 on-ear headphones offer a high quality, notably bass-forward, audio experience.

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Pros & Cons

    • Powerful audio performance with rich, full-bodied bass and solid balance between lows and highs.
    • Detachable cable with inline remote and mic.
    • Doesn't include many accessories.
    • Purists might find the sound a bit bass-heavy, lacking at times in the higher frequencies.

KEF M400 Specs

Boom Mic
Phone Controls
Removable Cable
Type Supra-aural (on-ear)
Wireless

KEF recently updated its headphone lineup, with the on-ear M400 among the notable additions. At $249.99, the M400 is priced to compete with some of the more luxurious offerings on the market from Sennheiser and Bowers & Wilkins, and while the headphones may not blow the competition out of the water, they can certainly hold their own. Purists might find the M400 a bit too bass-forward, but this sound signature will appeal to many listeners. More high-frequency presence, and perhaps a more compelling accessory range, given the price, would be appreciated. But overall, the KEF M400 delivers a strong audio performance.

Design
Available in black, blue, orange, or white, the lightweight M400's matte finish of brushed metal and leather gives it a sleek, minimalist look. Its supra-aural (on-ear) design feels quite comfortable thanks to ample cushioning in the perforated leather earpads, although the headband lacks much in the way of padding and its rubberized underside can feel like it's pressing on your scalp over long listening periods. A pivoting connection point for the earpads allows for a secure on-ear fit, though it would be nice to see stop points on the headband to allow for precise adjustment. Beneath the earpads, each ear houses a 40mm neodymium driver.

An inline remote control (with mic) is situated at roughly chin-height along the detachable cable, which connects to the left earcup. The remote is of the three-button variety, with a multifunction button for playback, track navigation, and call management, and two dedicated buttons for volume control (which work in conjunction with your mobile device's volume). At this price, an extra cable would be nice.KEF M400 inline

A small cloth zip-up pouch is bundled with the M400—the headphones fold down at joints on the headband to fit inside. Also included: an airline jack adapter, but oddly, no ¼-inch headphone jack adapter for stereo systems and pro gear.

Performance and Conclusions
On tracks with sub-bass content, like The Knife's "Silent Shout," the M400 delivers robust, deep bass response, and doesn't distort at top listening levels. At moderate volumes, the sense of fullness in the lows is still very much present, though at times on this track, the lows almost seem to overpower the highs slightly.

Bill Callahan's "Drover," a track with less in the way of deep bass, gives us a better idea of the M400's overall sound signature. The drums on this track receive a healthy dose of low-end boosting—not so much that they overpower the mix, but this is certainly a bass-forward sound, which also ends up giving Callahan's baritone vocals some extra—if unnecessary—richness. The guitar strumming on this track could be a tad brighter, but it doesn't sound dulled—it's still fairly crisp and very much part of the mix. Callahan's vocals also receive a bit of high-mid edge to help them remain clear and well-defined. Things never sound muddy, but the balance of the sound signature does seem to favor the lows and low-mids.

On Jay-Z and Kanye West's "No Church in the Wild," the kick drum loop's attack gets enough high-mid presence to sound sharp and punchy, but it could benefit from even a little more treble edge, as there's plenty of low and low-mid frequency presence to contend with. The sub-bass synth hits on this track are delivered with depth and power, and the sustain of the drum loop also gets some extra body thanks to the bass-boosted sound of the M400.

On orchestral tracks, like the opening scene in John Adams' The Gospel According to the Other Mary, the M400 keeps the spotlight on the higher-register strings, brass, and vocals, all of which retain their brightness. The lower register instrumentation, however, gets plenty of added depth here, bringing it forward in the mix a bit. This may not be a sound that appeals to purists seeking flat response, but those who like a little added bass depth and richness without things going too far will likely enjoy the M400's overall sound—though a little extra high-mid presence would balance things out a bit more.

In this price range, there are several on-ear options we think offer a great audio experience—the Bowers & Wilkins P5 Series 2, Beyerdynamic T 51 i, and Sennheiser Momentum On-Ear all are strong options with varying degrees of bass and treble balance. If you're looking to spend less money, consider the Marshall Major II, which delivers a solid on-ear audio experience for the price. It's hard to knock the KEF M400 for much other than being a bit light in the accessory department for a $250 pair of headphones. From an audio standpoint, the M400 delivers a bass-forward approach that will appeal to plenty of listeners, and whether you find yourself yearning for a bit more high-mid presence is more a matter of personal listening preference than a comment on the quality of the audio.

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Further Reading

Final Thoughts

KEF M400 - KEF M400

KEF M400 Review

4.0 Excellent

A little light on accessories for the price, KEF's M400 on-ear headphones offer a high quality, notably bass-forward, audio experience.

Get It Now

Buy It Now

About Our Expert

Tim Gideon

Tim Gideon

Contributing Editor, Audio

My Experience

I've been a contributing editor for PCMag since 2011. Before that, I was PCMag's lead audio analyst from 2006 to 2011. Even though I'm a freelancer now, PCMag has been my home for well over a decade, and audio gear reviews are still my primary focus. Prior to my career in reviewing tech, I worked as an audio engineer—my love of recording audio eventually led me to writing about audio gear.

My Areas of Expertise

  • Headphones and earphones
  • Wireless and computer speakers
  • USB mics
  • Bluetooth headsets

The Technology I Use

Probably because of their prevalence in the recording studios I worked in a long time ago, I am most comfortable on Macs—I'm writing this on the 2019 iMac I use for testing. I also have a MacBook Pro that gets plenty of similar use.

My workspace has a mini recording studio setup, and the the gear I work with there is a mix of items I've used forever (Paradigm Mini Monitors and a McIntosh stereo receiver) and newer gear I use for recording and review testing (such as the Universal Audio Apollo x16).

I'm obsessed with modern boutique analog synths—some of my favorites instruments in this realm are the Landscape Audio Stereo Field and HC-TT,  the Soma Enner, the Koma Field Kit, and the Lorre Mill Keyed Mosstone.

From my studio days, I'm comfortable using Pro Tools, and in recent years have branched out to other realms of creative software, like Adobe Premiere and After Effects.

I stream music, but I also still buy albums, digitally or on vinyl, and encourage anyone who wants fair compensation for musicians and engineers to do the same.

I also play lots of Wordle.

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