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(Pocket-lint) - Good in-ear headphones have always been able to deliver decent levels of bass thanks to their proximity to your ear and tight seal. But the majority of pairs still lack real driving power, which is something you can only really get from a pair of on- or over-ears.

Denon is hoping its latest pair of in-ear headphones, the AH-C821, can buck that trend and conjure similar levels of power thanks to a new design approach that places two drivers in each earpiece, one in front of the other.

Is this a method of madness or has Denon struck a real turning point for affordable in-ear headphones?

Denon AH-C821 review: Design

  • Total weight: 10.4g
  • Aluminium housings
  • Included Comply Foam tips
  • Four pairs of silicone tips also included

Everything about the Denon AH-C821 screams premium. From the moment you pick up the box, which itself has a nice weight to it, to the moment you put them in your ears.

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The AH-C821 come wrapped around a soft silicone wheel, which is also the carry case, and are pre-fitted with Comply Foam ear tips. If you've never used Comply tips before, they're made of foam which you need to squeeze before you put them in your ears. They then expand to fill your ear canal and create a tight seal for the best possible sound. Also included are four pairs of silicone tips, which are much easier to wash.

When the C821s are in your ears, you do notice they're there as they're not the lightest in-ears ever, but it's not enough to put us off. They're made of aluminium and because of the driver array inside the earpieces, they're able to sit more flush with your ears than most other pairs, so they won't stick out too far.

Even the cable exudes a premium feel. It's not your usual cheap-feeling wire or fabric. Instead it's a tangle-free rubberised cable that has a lovely gunmetal colour finish. Denon has split the cables going to each earpiece in two, so each driver gets its own cable. It's the first time Denon has done this to help minimise any unwanted interference. We like the results it provides.

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There's no control buttons or microphone along the cable, so if you receive any phone calls while listening you'll have to take the in-ears out to take the call. And, of course, all control of your music has to be done via your smartphone our music player.

Denon AH-C821 review: Sound quality

  • Denon patented Double Air Compression driver
  • Acoustic Optimiser for improving power and detail
  • Two 11.5mm drivers in each ear piece

When you first put the AH-C821 into your ears, you probably won't be prepared for just how loud they can go. We weren't, that's for sure. We went with a good test of drums and bass with Mombasa from the Inception soundtrack. Initially we thought what we heard was good, but not that loud, then "bam!" the power Denon promised with the new driver array hit our ears.

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Even at high volumes we were rewarded with clarity and detail. From our experience with some other in-ear headphones, turning the volume up on your phone can often cause them to buckle under the pressure and distort. We faced no such issues with these Denons, they simply took everything in their stride.

You can clearly pinpoint different instruments, backing vocals and leads, such are the Denon's placement skills, that you really will be immersed in whatever you listen to. There's a great sense of rhythm from them too, they're an exciting listen that move along with speed and gusto, but never getting ahead of themselves. They're entertaining and, although it sounds cliche, made us fall in love with our music collection all over again.

Denon AH-C821 review: Features

  • Denon Audio iOS and Android app
  • Software equaliser (£1.49 extra)

You may think that the C821s are just another regular pair of wired in-ear headphones, with not much else going for them.

However, Denon has a companion app for iOS and Android that not only acts as a music player, but lets you adjust the equaliser settings for whatever you're listening to. You can either choose one of the preset settings or manually adjust it to your heart's content, although you will need to pay £1.49 for the privilege (we're baffled it's not included with purchase). You can, however, download the app and use it as a regular music player without the equaliser adjustment free of charge.

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A lot of our music is on Apple Music, which the Denon Audio app can access but can't play such tracks because they either can't be fully downloaded from the cloud or are DRM protected. Fortunately we did have a few purchased tracks, so could play about with the sound settings.

You can also access TuneIn radio through the Denon Audio app, giving you access to myriad internet radio stations, for which you can again adjust the sound settings.


The Denon AH-C821 in-ears are exceptional in-ear headphones. From the moment we put them in our ears fell in love and didn't want to take them out. We love their premium look and finish, their fit and , ultimately, the sound they produce.

It's only some app foibles and the price that work against them. At £169 they're pricey, but the audio upgrade they offer over the free headphones you get with a smartphone is mind-blowing. We think they're worth it - especially if you can find them for less cash.

You can buy the Denon C821 now from Amazon.

Writing by Max Langridge. Originally published on 13 January 2017.