KEF Mu7 in the test: The pressure comes when they are loud

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KEF Mu7: Does the noble design come with a noble sound?

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Matthias Kremp / DER SPIEGEL

I have a changeable relationship with the KEF company.

In the early 1980s, a pair of KEF C20s were the first good speakers I could afford with summer job wages.

To this day I'm still annoyed that years later I gave them away in a barter.

At the beginning of the corona crisis, after a long KEF break, I was able to test a pair of networked speakers from the LSX series and was very impressed.

I hadn't noticed that the company now also makes headphones.

So it's only logical that I didn't hesitate when the company announced the Mu7, over-ear headphones with active noise cancellation.

Their design looks very organic, the choice of materials with aluminum and memory foam is of high quality.

The price of 399 euros raises high expectations.

So I took the KEF headphones to the test track, not only in the home office but also on the go.

rumble and rumble

On a train journey from Hamburg to Berlin and back, I was able to try out the noise suppression “live”, so to speak.

The result was not quite as hoped: the electronics of the Mu7 only moderately dampen external noise.

They got the deep rumbling of the ICE well under control, but overall the driving noise was still easy to hear despite the combination of passive and active insulation.

They also produced a clattering noise, like grates shaking, that couldn't be heard on the train without the headphones.

My AirPods Pro 2, which I took with me for comparison, did a far better job of almost dying out the rumbling and roaring of the wagons.

15 minutes of charging is enough for a flight to New York

What I didn't need so much on the train journey are the cables and adapters that came with it.

For example, I only use the USB-C cable once before I leave to charge the batteries in the headphones.

According to KEF, one charge should last for up to 40 hours of listening to music, and 15 minutes on the charger should provide enough power for eight hours, which could be enough for a transatlantic flight.

I could not verify these numbers.

While I must have listened to music and watched movies for two to three dozen hours with the Mu7, I only charged it that one time.

Unfortunately, there is also no way to display or announce the charge level.

So it can easily happen that you are left without any residual energy.

They have to be loud

But let's get to the most important thing: How do the KEF actually sound?

In the 2018 remix of Pink Floyd's "Dogs", the sub-bass synthesizer pushing from far below is only vaguely perceptible during the synth solo.

Everything that is above that in the frequency ranges is reproduced extremely cleanly by the Mu7.

This is also wonderful to hear on Morcheeba's »World Looking In«, where both the vocals and the bottleneck guitars shine beautifully.

You can hear the bass and kick drum, but they sound a bit like a flat tire: depressurized.

The Mu7 only convey pressure when I turn the volume up to at least three quarters of the maximum volume.

Don't worry, I didn't damage my ears because these headphones aren't particularly loud even at full speed.

But if you push the volume control towards full steam, they clearly gain in assertiveness, the basses are also a bit oppressive and the sound becomes livelier.

Based on an old Grönemeyer song: I only like the KEF when they are loud.

Voice stings office noise

KEF hardly says anything on its website about the fact that the Mu7 can also be used to make calls via smartphone. It is only pointed out once that calls can be accepted and ended via the touchpad.

The sound quality during phone calls is remarkable.

In my tests, my voice was clearly recorded by the built-in microphones.

According to KEF, a technology called "Clear Voice Capture" helps to acoustically separate the voice from ambient noise and at the same time reduce street or office noise.

Of course, said touchpad has even more functions, it can also be used to control music playback.

Swipe up or down to increase or decrease the volume, swipe left or right to skip or replay songs.

The system is known from many other headphones.

So it's not surprising that longer pressure on the touchpad calls up Siri or the Google Assistant, depending on the smartphone.

Conclusion

Compared to headphones like the WH-1000XM5 from Sony (here is our test) or Apple's AirPod Max (here is our test), the KEF Mu7 are comparatively restrained.

Their sound is clear and unexcited up to medium volumes, and the right atmosphere only comes about when you let them get loud.

Some listeners may not like that, at least not immediately.

Coupled with the extremely soft ear cushions, this sound characteristic ensures that you can still listen to KEF's headphones in a relaxed manner, even over longer distances.

If you prefer more pressure or more volume, you'd better use the models from Sony and Apple.

Some are currently significantly cheaper, others much more expensive than the KEF.

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