Denon AH-C620 (AH-C621R) review

Denon does it again with these decent-sounding buds

TechRadar Verdict

The Denon C620s are packed with audio goodness that transcends their relatively cheap price. While sound quality doesn't quite reach the heights you hope, these are earphones that do reach beyond their price range.


  • +

    Comfortable to wear

  • +

    Great for the price

  • +

    Hi-res range level


  • -

    Design a bit too understated

  • -

    Controls too plasticky

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The mid-range in-ear market is perhaps the toughest to quantify for the regular headphone maker. The devices on offer aren’t quite cheap enough to warrant an impulse buy, nor are they expensive enough to be that ultimate Christmas or birthday purchase. So, for a pair of buds to standout in this price range, they have to take the Goldilocks approach and balance decent features with solid sound to create a device that’s ‘just right’.


Enter the Denon AH-C620 (known as the Denon AH-C621R in the UK) range. These are the sensible sibling to the higher-priced Denon C821R that impressed us earlier in the year. 

Box-wise and build quality, there’s not much between the two - despite these Denons being almost half the price. 

You get a rubber tidy case (a bag would have been more preferable but it does stop cable tangle) as well as a five extra pairs of earbuds, all designed for slightly different ear canal entrance sizes. One of these are the Comply TX400s which are by far our favorite tip when it comes to in ears thanks to their ability to expand in the ear and create a much better seal. 

The Denon C620s are deceptively light. Put them on and you'll be able to wear them for long periods as there aren't additional drivers to bulk up the earbud. You'd think there was, though, with the sound that comes out of them. 

These earphones are a great exercise in subtlety by Denon. They aren't flashy to look at, with design flourishes kept to a minimum. But everything seems to have a purpose. A toggle, for instance, is tucked flush to a small aluminum pole that supports the cable split for both ears. If you don't want as much loose cable, simply move this up to a place comfortable for you.

On the left earphone cable is the mic, volume and play/pause controls - for use with iOS devices - again styled simply. We're not impressed with the plastic feel of this control. It's by far the cheapest-feeling part of earphones, which is a shame when it's the bit you'll be touching most often. 

Other minimal design additions include a Denon logo on the front of the aluminum and resin shell of each bud and a straight 3.5mm gold-plated connector. 

The cable is long enough at 1.3m and Denon has added its Radial Cascade Damper system to the cable, too. This fancy name essentially means that you won't get cable noise with these earphones. In our tests this was indeed the case. 

When we figuratively dived inside the earbuds we were impressed with what we found. There's a modest 11.5mm driver in each bud and, with just 16 ohms of impedance, you shouldn't have any trouble at all driving these earbuds.

Surprisingly, given the lack of a Hi-res sticker these earphones, range wise at least, can handle frequencies of between 6-40,000Hz. At this price point, that makes the C620s a very enticing in-ear buy.

On paper, then, the stats are impressive. But, as always, the proof is in the listening. 


The Denon C620s haven’t been tuned for any specific range - unlike some other bass-hungry brands - and there’s a very good reason for this. The earphones come with an accompanying app. Called Denon Audio, the application acts as a conduit for getting the exact sound you want out of the headphones. 

The idea here is that, whatever music you have downloaded to your phone (it’s both iOS and Android compatible), you can load the app up and intricately play with the EQ settings of any song of your choosing. 

This isn’t an app built purely for these earphones but all Denon products, which means that it can seem a little overkill to load it up for the C620s, but we had a lot of fun tinkering. It’s just a shame that it doesn’t allow streaming services within the app, although there is access to TuneIn’s vast array of radio channels.

As for what we listened to, we always try a variety of genres and tracks to hear what gets the best out of the earphones we review (see the boxout) - these are what stood out for us.

The woozy calypso beat of Four Tet’s Love$ick remix fared well. The drums sounded clear, while A$ap Rocky’s rapping cut nicely through build up of base and, er, wind chimes. While there wasn’t quite enough oomph when the bass rumbled in, everything sounded crisp.

To warm things up a little, To Be Without You by Ryan Adams was a good test of the mid range, the earbuds managing to separate his acoustic guitar from Ryan’s vocals well. The more bass-laden Soothing by Laura Marling tested the lower range, and the C620 series passed admirably. 

Unfortunately where they slipped up was when we tried tracks packed with a bit more of a gut punch. Ham Zimmer’s Supermarine is one of the most intense scores out at the moment and that intensity was a little lost on these earbuds. Clarity was there but it lost the earthy gravitas of the track. 

Century by Feist did have the propulsion we wanted, though, but this is a song that's much more grounded and a little more drum heavy. 


We've been using the Denon C620s for the best part of a month now and what started out as a dependable pair of earphones have become our go-to when we don't need the safety of a pair of over ears, Bluetooth and noise cancelling. 

The sound they pipe out is better than we'd expect for this price range and wearing them for long journeys isn't an issue - they're so lightweight it takes a long time before you feel any sort of pinch or discomfort. 

The carry case is an issue - it's just not as aesthetically pleasing as putting your earphones in a pouch - but it does keep them tangle free. 

And if you're an Android user it's worth keeping in mind that the toggle controls will be limited to play and pause.

But despite these niggles, the Denon C620s pass the Goldilocks test with flying colours. 

Marc Chacksfield

Marc Chacksfield is the Editor In Chief, at DC Thomson. He started out life as a movie writer for numerous (now defunct) magazines and soon found himself online - editing a gaggle of gadget sites, including TechRadar, Digital Camera World and Tom's Guide UK. At Shortlist you'll find him mostly writing about movies and tech, so no change there then.