Astell & Kern AK HC5 review: a tiny DAC for a huge improvement on your phone's music, but it’s insightful rather than impactful through the bass | Tech Radar

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I tested it, and Astell & Kern’s new pocketable smartphone DAC is a clear winner for detail, marred just slightly by bantamweight bass

A&K is trying to bring some of its hi-res player magic to your humble phone…

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No, it’s not perfect. But by prevailing portable headphone amp/DAC standards, the Astell & Kern HC5 is very competitive in most respects — and it’s a lovely device to look at and to hold, too. With a little more low-frequency presence and positivity it could make the leap to a full five-star recommendation.

+Great specification matches the standard of build and finish

Great specification matches the standard of build and finish

+Far more portable than its most obvious price-comparable rivals

Far more portable than its most obvious price-comparable rivals

-Sounds slightly underwhelming at the bottom of the frequency range

Sounds slightly underwhelming at the bottom of the frequency range

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Astell & Kern builds some outstanding digital audio players, and the company also knows how to charge us for them. But it’s taken pity on those of us without the wherewithal, and has developed this HC5 headphone amp/DAC.

It is a portable device intended to transform your bog-standard smartphone into a viable source of hi-res audio for anyone with the wired headphones good enough to take advantage of it. With high-end AKM digital-to-analog conversion components on board, Astell & Kern’s ‘digital audio remaster’ and ‘high driving mode’ technologies included, and both balanced and unbalanced headphone outputs, the HC5 is specified to get the job done. It also features half- a-dozen digital filters, as well as a huge range of volume adjustment and some slightly imprecise-feeling physical controls that serve to undermine the robust and tactile overall nature of the device just a little.

In operation, the Astell & Kern is slightly lightweight at the bottom of the frequency range — it doesn’t have quite the heft or substance that it really should have, and can lack a little apparent punch as a result. In every other meaningful respect, though, it’s a very accomplished device indeed. It’s dynamic, lavishly detailed, creates a large and well-organised soundstage, and communicates through the midrange like nobody’s business.

If you want to turn your humble smartphone into a device that bears comparison with some of the best three-figure digital audio players around, and if you have suitable headphones too, then you ought to be after one of the best DACs around. And you should absolutely hear the Astell & Kern HC5.

Astell & Kern AK HC5 review: Price & release date

The Astell & Kern HC5 headphone amp/DAC launched at the very end of 2025 and hit shelves in January 2026.

In the United Kingdom it sells for £399. You’ll need to part with more like

This makes it a reasonable (rather than 'cheap') option, of course — at only

Apparently this is the first time that AKM’s flagship AK4191EQ digital processor and AK4499EX digital-to-analog converter have appeared in a product as small and as relatively affordable as this one. AKM suggests that splitting the d-to-a decoding into two stages preserves signal integrity — and Astell & Kern agrees. Mind you, that hasn’t stopped Astell & Kern bolstering the AKM chipset with its own ‘DAR’ (digital audio remaster) upsampling technology; it functions with both PCM and DSD content, increasing the sampling rate by quite a degree, and it can be switched off if you so desire. The upshot, though, is a DAC that supports 32bit/768k Hz and DSD512 resolutions.

Astell & Kern’s ‘high driving mode’ technology is also making its debut appearance in an affordable product. The horizontal op-amp layout helps keep the physical size of the HC5 to a minimum, but also allows for significant driving power. It's worth bearing in mind, though, that the HC5 has no power supply of its own, and the prodigious amplification power it can muster will cut into the battery life of your source player more than somewhat.

There are a total of six digital filters for the user to explore, but this is the extent to which you get to influence the sound of the Astell & Kern. Perhaps oddly, there’s no sign of the EQ adjustment that’s commonplace on quite a few of the HC5’s nominal rivals.

Bantamweight rather than heavyweight where bass is concerned

The proof that the digital-to-analog conversion abilities of your smartphone or laptop are pretty rotten can be found in the number of extremely affordable USB DACs that are on sale now — Tech Radar has rounded up the best of them, as I've previously alluded to.

But there’s no denying that spending $489 / £399 (or equivalent) on an Astell & Kern HC5 takes the sound of your laptop or smartphone to another level entirely. Provided you have the headphones to properly exploit its talents, anyway.

Load up a 24bit/48k Hz FLAC file of Off Course by Oh Sees and all will rapidly become clear. When it’s dealt with by the HC5 the recording is more open and spacious, and yet somehow more singular and unified at the same time. The soundstage from which it comes is big in every direction, and the spaces and silences on it suddenly become almost as significant as the actual occurrences. Each participant has more than enough room in which to operate without crowding any other.

There’s real positivity and energy to the way the Astell & Kern delivers the recording, a sense of engagement and enthusiasm which is strongly at odds with the sound served up by a bog-standard smartphone. But at the same time the presentation is poised and balanced despite its direct and upfront nature — there’s never any suggestion the HC5 is not fully in control. This authority is especially apparent at the bottom of the frequency range, where the attack and decay of bass sounds is observed with such care that rhythmic expression is always confident and naturalistic. Down at the bottom end is where the Astell & Kern’s most significant shortcoming lurks, though. Just like the rest of the frequency range, the low end is lavishly detailed where timbre and texture are concerned — there’s more than enough information revealed and contextualised to let you know you’re getting a very full account of a recording. But there’s an appreciable shortage of body and substance to the low frequencies the HC5 generates. It can dig respectably deep but it doesn’t hit as hard, or with as much weight, as is ideal.

Otherwise, though, the frequency response is just as pleasing and convincing as everything else about the Astell & Kern. It’s articulate through the midrange, communicating the attitude and intention of a voice every bit as willingly as it reveals the details of tone and technique. The top of the frequency range is bright and similarly detailed, but carries enough substance along with it to prevent it sounding thin or aggressive — and this is true even if you like to listen at considerable volume.

There’s ample dynamic headroom available for when the attack or intensity or simple volume of a recording ramps up, and a similar facility with the less obvious (but no less important) dynamics of harmonic variation. It’s not enough for the HC5 to identify and reveal the most fleeting, most minor details in a recording - it is able to put them into the sort of context that means they serve as part of an overall picture, rather than treating them like some kind of academic exercise.

There’s ‘portable’ and then there’s the Astell & Kern HC5. Unlike quite a few nominal rivals, (some of which look like hip flasks) this headphone amp/DAC is sufficiently small (64 x 32 x 16mm, Hx Wx D) and light (46g) enough to be taken out even by those not wearing a coat with sturdy pockets, or carrying a bag of some kind.

The aluminium construction is impeccable, the proportions are almost instinctively suitable for a palm, and those concave sides only add to the tactility. Obviously Astell & Kern is a past master at this sort of thing, but it’s nice to be reminded it can do it for a £400 product as readily as it can for something costing £4K.

At one end the HC5 has a USB-C input — it’s supplied with both USB-C / USB-C and USB-C / Lightning cables, so you should have no problem connecting your source of music. At the other there are 3.5mm unbalanced and 4.4mm balanced headphone outputs.

Next to the USB-C input there’s a relatively large, knurled dial that takes care of volume — the HC5 features a frankly excessive 150 steps for ultra-granular control. It feels just slightly wobbly and a little less premium than the main body of the device.

That’s also true of the little button on the side of the HC5 that is basically your control for everything that isn’t volume; it feels just fractionally imprecise. Thankfully the display it works in conjunction with, which occupies fully half of the front of the device, is crisp and bright and legible. Here’s where you’ll turn the digital audio remaster algorithm on or off, and choose between the six available digital filters — and this, in essence, is what constitutes ‘set up’ where the Astell & Kern is concerned.

It more than levels up your phone's audio without you noticing it's there

If — and it’s quite a big ‘if’ — you have wired headphones capable of taking advantage of the HC5’s unarguable sonic abilities, and if you have a streaming service subscription that includes lots of hi-res content, then there’s no arguing with the difference the Astell & Kern can make to your portable listening experience. Which has to count as ‘value’ in anyone’s language, doesn’t it? OK there are cheaper devices out there too, but none look or feel quite as good as this one — and there are also much more expensive ones out there…

You own good wired headphones Because no good can come of plugging them straight into a smartphone

You have access to truly hi-res content The HC5 can deal with the biggest real-world resolutions around

You think ‘portable’ should mean ‘portable’ Small and palm-sized, the A&K can genuinely go anywhere without becoming a burden

Your headphones are on a 6.3mm jack You’ll need an adapter to use them with the HC5

You place a lot of value on the physical interface The feel of the physical controls isn’t as premium as it might be

Your source player doesn’t have huge battery life The A&K uses your player’s power, and quite a bit of it

Where price and performance is concerned, the most obvious rival to the Astell & Kern HC5 is the Chord Mojo 2. In absolute terms it probably has the edge over the HC5, and its EQ adjustment facility is worthwhile too — but it stretches the meaning of the word ‘portable’ quite a distance…

At one end I connected the Astell & Kern HC5 to an Apple i Phone 15 Pro, a Fii O M15S digital audio player, and an Apple Mac Book Pro — this way I was able to access a whole lot of content of various genres and resolutions, and also to assess the device’s performance against the extremely impressive D-to-A abilities of the Fii O DAP.

At the other end I connected a pair of Austrian Audio The Arranger open-backed over-ear headphones to the 3.5mm unbalanced output and a pair of Sennheiser IE900 in-ear monitors to the 4.4mm balanced alternative.

Simon Lucas is a senior editorial professional with deep experience of print/digital publishing and the consumer electronics landscape. Based in Brighton, Simon worked at Tech Radar's sister site What Hi Fi? for a number of years, as both a features editor and a digital editor, before embarking on a career in freelance consultancy, content creation, and journalism for some of the biggest brands and publications in the world.

With enormous expertise in all things home entertainment, Simon reviews everything from turntables to soundbars for Tech Radar, and also likes to dip his toes into longform features and buying guides. His bylines include GQ, The Guardian, Hi-Fi+, Metro, The Observer, Pocket Lint, Shortlist, Stuff T3, Tom's Guide, Trusted Reviews, and more.

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Key Takeaways

• News, deals, reviews, guides and more on the newest computing gadgets

• Start exploring exclusive deals, expert advice and more

• Unlock and manage exclusive Techradar member rewards

• I tested it, and Astell & Kern’s new pocketable smartphone DAC is a clear winner for detail, marred just slightly by bantamweight bass

• A&K is trying to bring some of its hi-res player magic to your humble phone…