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KEF M400

On-ear headphones with Apple® remote and microphone (Racing Blue)

Item # 991M400BL

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Was: $249.99

Price break: -$100.00

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Our take on the KEF M400

We've long admired KEF from a distance. These British audio specialists have spent decades making great-sounding, cool-looking speakers. So when we started carrying them, and I got my hands on a pair of their M400 on-ear headphones, it was kind of a big deal.

Sleek, lightweight headphones from the storied sound experts

We've long admired KEF from a distance. These British audio specialists have spent decades making great-sounding, cool-looking speakers. So when we started carrying them, and I got my hands on a pair of their M400 on-ear headphones, it was kind of a big deal.

Once I tried them out, I immediately understood how KEF earned their sound reputation. These headphones — designed by Studio F.A. Porsche in Austria — feel really well-made. They are smooth yet extra-solid, both in terms of build and style.

KEF M400 on-ear headphones

The KEF M400 on-ear headphones sit a little further back on your head, helping create a tight audio seal and form-fitting look.

Comfortable and secure, with a unique fit

I sort of had to learn how to wear these headphones. Their firm aluminum headband didn't quite fit like most, resting a bit to the back of my head rather than at the center of my crown. But I only had to adjust the free-wheeling earcups a little to find the sweet spot of comfort. I quickly got used to them, and appreciated how well they stayed put — never moving around, even when I shook my head to test them.

At a glance, the earpads don't seem any more cushioned than your average on-ear headphone — but boy, are they. Extra-soft memory foam is wreathed by plush, perforated leather that protects your ear for a tension-free fit. The leather-lined headband never felt like it was clamping, even though it fit snugly to prevent sound from escaping. I think it's because the M400s sit a little further back. 

Dynamic sound with deep, detailed bass

Spotify® recently started serving up something called Release Radar, a weekly, personalized playlist of new songs from your “saved artists” list. It's a good way for me to test headphones because it usually features different-paced songs that span all genres. From stripped-down acoustic recordings to (frankly) over-produced studio tracks, the M400s made sure everything sounded it's best.

Schoolboy Q's hypnotic “THat Part Remix” proved the M400s were capable of reproducing bass that's both hard-hitting and nuanced. Next, a more upbeat, guitar-driven David Bowie live recording opened the soundstage up to show off the headphones' realistic sense of space. Considering how compact these headphones are, it was a bit surprising how spread out everything sounded.

Product Highlights:

  • closed-back, tightly-sealed on-ear design blocks out external noise
  • 40mm dynamic drivers deliver detailed sound with powerful, nuanced bass
  • sturdy, precision-machined aluminum frame keeps headphones from moving around
    • leather covered headband
  • fluid, ball-jointed ear cups move to fit the shape of your ear
    • perforated leather earpads filled with memory foam for comfort and breathability
  • portable folding design
  • detachable 51-inch cable with miniplug connector
    • in-line remote and microphone for taking calls and controlling playback and volume on your iPhone®
  • airplane adapter plug included
  • zippered storage case
  • designed by Studio F.A. Porsche
  • frequency response: 20-20,000 Hz
  • sensitivity: 101.5 dB
  • impedance: 32 ohms
  • weight: 6.2 ounces
  • warranty: 1 year
  • Our 60-day money-back guarantee

What's in the Box:

  • On-ear headphones (Racing Blue)
  • 54" Audio cable with in-line remote/mic (3.5mm plug)
  • Airline adapter
  • Quick Start Guide
  • Important Safety & Warranty Information

Hands-on research

Features and Specs

Earcup Type Closed
Earcup Width x Height 2.087" x 2.792"
Noise-canceling No
Bluetooth No
Mic For Taking Calls Yes
iPhone Control Yes
Lightning Connector No
Android Control No
Frequency Response 20-20k Hz
Sensitivity 101.5 dB
Impedance 32 Ohms
Weight 6.7 ounces
Cord Length 54"
1/4-inch Adapter Included No
Volume Control Yes
Parts Warranty 1 Year
Labor Warranty 1 Year

Product Research


Overview: The KEF M400 Hi-Fi Headphones feature innovative design, precision engineering, and state-of-the-art technology to deliver high-resolution sound and hours of comfortable listening. These on-ear headphones have a precision-machined cast aluminum frame to give them a lightweight but solid feel. The ear cups are hinged to fold in for storage in the supplied soft cloth pouch. The M400s come with a 54" straight cable with in-line remote/mic and an airline adapter.

Drivers: The M400s feature full-range 40mm dynamic neodymium drivers with copper-clad aluminum wire (CCAW) voice coils for delivering the KEF signature sound.

Ear Cups: The ear cups are equipped with high density memory foam pads, which are covered with soft, sweat-resistant protein leather. The "race-track" design of the ear pads follow the shape of your ear and form an acoustic seal which shuts out external distractions by -20dB , and prevents sound leakage. The aluminum frame and soft ear pads ensure your comfort for hours of listening.

In-line Remote/Microphone: The M400s feature a 3-button remote and microphone for control of your phone calls and music playback. The remote is "Made for iPod iPhone iPad"-certified, and controls playback, Siri, and volume for Apple iDevices. It only controls play/pause and skip forward functions when used with Android devices. The 54" cable has straight 3.5mm plugs on both ends to let you put the remote/mic at either end.


  • Frequency Response: 20 Hz - 20 kHz
  • Sensitivity: 101.5 dB (+/-4dB at 1 kHz)
  • Impedance: 32 Ohms (+/-15%)
  • Maximum Input Power: 30 mW
  • Noise Attenuation: -20dB
  • Weight: 6.7 ounces

Our Product Research Team

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