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    KEF M400 Headphones - Expert Review

    KEF M400 On-Ear Headphone Review - Bantamweight Boogie

    British firm KEF has decided to follow up on its acclaimed KEF M500 on-ear model with a slimmer, lighter version. It's not easy to follow in the footsteps of a famous sibling, and the work is cut out for the KEF M400 in this regard. However the KEF M400 has form which exceeds its weight class and is a real contender. The M400 would make a terrible boxer as it often remains out for far longer than a ten second count; however it's got me right hooked. KEF M400


    • Small and light
    • Sturdy build and construction
    • Removable cable with mic/controls
    • Stylish understated design
    • Folds up for easy storage


    • Soundstage limited

    Design and Appearance

    The M400 model maintains a family resemblance with its flat ear cusions and swept back ear cups, but it is definitely a cut down version of the chunkier KEF M500. The headband is much thinner, plus the earcups are constructed from aluminium; they're misleadingly light!

    Durability & Build Quality

    Despite the lighter and sleeker construction, the M400 still feels like a solid headphone and a fitting follow-up for KEF. The cable is not thick, but has a hard-wearing feel about it with decent strain reliefs at each end. The mic/controls on the cable have no strain reliefs.


    First impressions were regarding the headband padding and size - with this reviewer being a bighead, the headband needed to be fully extended in order for the earpads to properly sit on the ears, and the headband makes itself known by applying pressure to the top of the head. having said that, they have remained in position for upwards of an hour now, with no significant discomfort.


    As a portable model, the M400 is ideal; it does everything well. It leaks very little sound even with a high volume level, it's light, can be worn around the neck unobtrusively and goes into the supplied carry pouch very nicely. The earcups are hinged so the M400 can easily be folded up, and it even fits in the case when the earcups are extended fully so the headband sliders don't need to be adjusted all the time. Perfect! KEF M400

    Sound isolation

    The KEF M400 does a fair job of keeping out exterior sounds; don't expect to be incommunicado as you listen to Marillion, but enough environmental noise is blocked to keep things enjoyable.

    Sound characteristics

    Overall, the sound is very similar to the M500 model in terms of balance. The M400 is a little lighter-sounding with not so much bass presence and subtler treble, for a slightly more neutral sound.
    • Bass
    Bass is still very much a part of proceedings, strongly underpinning the music without stealing the show; however there is a little looseness up at the top end of the bass end of things. Not enough to impinge on the midrange, however.
    • Mids
    The natural and effortless presentation within the midrange is what makes the M500 great, and the M400 is no different. Instruments jump out at the listener, taking on form and appearing very real without feeling forced. There's bags of room, and everything is nice and clear even with plenty going on.
    • Treble
    Treble is relaxed but tight and accurate. The M400 is a good choice for those with some sensitivity to higher frequencies, but who do not want to miss any details. Like the midrange, the higher frequencies are not forced but very effective at the same time. The treble puts the cherry on the midrange cake to reveal that last harmonic and render a presentation very convincing. KEF M400

    Soundstage & Separation

    Soundstage is fairly good, helped along by the clarity of the midrange. It is perhaps limited by the on-ear design when compared to a full-sized closed back, as the folds of the ear are flattened by the earpads' design and internal reflections are skewed somewhat. Separation is crisp and clear, with everything in place and well defined.

    Music genres good for and why

    Pop and rock are very good with the KEF M400; jazz, classical and acoustic may suffer slightly from a lack of soundstage relative to full sized or open headphones but this is a minor drawback. For a fuller bass sound maybe try the M500 model, but the M400 gives a good clean fight and only hugs my head as I enjoy the music!


    A good choice for those who like a smooth and trouble-free model; the KEF M400 is the perfect mixture of stylishness, sound quality and practicality. KEF M400

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