Astell & Kern AK Jr – Who You Calling Junior?


Standout back in 2013 was the AK100’s USB DAC capability. The original AK100 worked exactly the same way. Plug it in, wait for the charging indicator, then depress the mains button. Your choices: DAC, Charge, or data transfer, are simple and foolproof.

Jr’s USB transfer speed, however, is insanely slow. A 500 MB ALAC album takes about two minutes to download to the player. My 2011 iPod will transfer the same album in about 30 seconds. Dumping 32GB of random albums onto Jr took an hour and a half.

Battery life

In three unloaded mixed-format tests, AK Jr averaged 7 hours, 33 minutes of run time. When playing DSD files, that number drops to 5 hours and five minutes. 

NOTE I: DSD battery run down tests were conducted only twice before they were averaged.

NOTE II: This is a demo unit. It is possible that its battery isn’t optimal.


Jr looks great on paper and on computer screen. It hurts in the hand. But, once you cue up the song/album/artist you want, dim the screen, and unwind, it does what it is supposed to do: play music. To the techie music lover, its complete rocking of the WM8740 chipset makes up for its many shortcomings. To the just-want-to-enjoy-my-tunes music-lover, its UI-related flaws really need a fix.

Performance and sound

By the numbers, I would expect players costing thousands more to walk all over Jr. And while both the AK240 and AK380 can and do outperform Jr in a number of measurable areas, I’ll be damned if you, or I, can hear most of them.

Sound signature, however, is another thing.

Jr has this warm, dry thing going on that stands distinct to A&K’s latest DAPs. The AK380, for instance, is more contrasty. And since I called Jr ‘dry’, I’ll probably should call the AK380 ‘wet’. Of course, both adjectives oversimplify reality, and draw distinction to nearly hyperbolic lines. That said, the comparison stands. And for its sake, Jr is warm and dry and AK380 is contrasty and wet.

Jr nails the authoritative, muscular sound for which many Wolfon DACs are known.

It is coupled to a practically hiss-less output that is perfectly suited to sensitive earphones such as the Ultrasone IQ and the Shure SE846. It outputs about as much hiss as an iPod nano 7G and just a bit more than the Calyx M.

Jr’s volume range arrays itself over 150 steps, labelled in half stops from 0 to 75. Finding the right volume for your earphones, or your headphones, is as easy as pie. And unlike either the AK380 or AK240, maxing the volume (or setting it to line out) doesn’t result in audible increases in distortion. Both the AK380 and AK240 suffer from intense, ratcheting IMD and THD, that, even when driving unloaded signals, can result in audible shearing and sizzling. If you’re going to use outboard amps connected via line out, Jr is far better suited.

Or, you could lower the volume of either high-end AK device to obviate distortion. Doing so, however, nets compressed dynamic ranges, stereo separation, and more.

But let’s get back to music.

When feeding my Ultrasone IQ something from Armin whilst sipping gin on my porch, I’m most comfortable tuning Jr to volumes between 20 and 24. Whilst sipping from a snifter on the train, or airplane, I bump it up to a maximum of 35. And naturally, Jr is perfectly balanced in both channels from the getgo.

The sound stage Jr throws is wide and tall wall, a wall-of-sound that maximizes surface area in lieu of ploughing deep z-axis fields. That wall of sound starts from the centre of the head and moves out by dozens of centimeters on either side and about ten centimeters above the head. Like the DAC that drives it, it is dry land muscular.

And yes, that sound stage is an audible upgrade to the original AK100 and to the iPhone 4s. Its warmer signature reminds me of the original iPod nano. Except its output is much less hissy, and its line far cleaner and its headphone output far better able to handle varying loads.

Astell & Kern’s marketing literature suggests that Jr’s output impedance is 2Ω. It handles hard, high-current loads well but not perfectly. Its most obvious artefacts are, small treble rises when paired with earphones with wildly swinging impedance curves such as the Earsonics SM2. That said, the differences are so minute that I doubt anyone reading this review could suss them at the ear.

Unlike Apple iPhones and iPods, it blasts way, way beyond the 110dB barrier of dynamic range, stereo separation, and noise. While it appears to post THD and IMD levels about 10x higher than the AK380 and AK240, I will again argue that the levels detectable by the Lynx HILO (~0,036%) are inaudible. Under hard, high-current, low-Ω headphones such as the Audio Technica ES7, THD will max at of over 1%, and may be audible to some.

Overall, Jr impresses. Its output is strong all the way up to 75. And it gets loud, and bides very little distortion. It is warm, dry, and perfect for trance, EDM, classical, jazz, vocal, and John Denver. If you’re heavily into motion picture soundtracks, or strongly emotive genres, who knows: you may enjoy Jr as much as I do for the stuff I enjoy. And you may have a different headphone setup. All I can say is that this thing is well done.


Jr’s equaliser is five band. It sidesteps sizzlies by lowering amp gain by about 3 decibels prior to making any audio adjustment. Bass appears not to distort when set to maximum, but treble can induce a LOT of IMD. Used in moderation, it is decent, and can twang up your music. Honestly, I’m not a big EQ guy, so I’ve largely let it alone except to ensure that it doesn’t muck up music too much. And it doesn’t. At least, not too much.


While Jr doesn’t have a huge amount of overhead for high-impedance, low-current headphones such as the DT880, it supplies ample volume and low distortion levels all the way to volume 75. Personally, I can’t stand the DT880/600 and Jr combination at volumes of over 62 for older recordings and 58 for newer recordings. Chase Emory probably will max Jr out.

Jr’s dry warmth fits the DT800’s contrasty signature very well. Mr. Speakers Alpha Dog headphones also sound good, but are equally as comfortable with the smoother AK380.

As for earphones, there is a break in performance when an earphone dips below the Jr’s 2Ω impedance output. Even then, it is minimal. But to be safe, you’ll want to use earphones with really flat impedance swings.

Honestly, I fell in love with the Jr through the Ultrasone IQ and the Grado GR10. Despite the two sharing little in common, the contrasty-VS-midrange IQ signature benefited from the Jr’s warm bass. And the GR10’s wide midrange benefited from Jr’s wall-of-sound sound stage. And I’m a Grado guy.

It is my personal opinion that Jr fits the signature of neutral to contrasty headphones very well. Warm headphones and earphones sound good through it, but compound Jr’s already warm personality.

VS the iBasso DX90

NOTE: read Lieven’s comparison review of the DX90 and DX50. Then read my ode to the DX90 with Rockbox.

Before I get really into this, note that I don’t consider these players to be competitors. iBasso’s DX90 is an incredible machine. But it is a techie-oriented DAP: removable battery, hackable hardware/software, a nearsighted engineer’s design perspective, coaxial output, and a company behind it that is interested in price/performance ratios first, everything else second. In general, iBasso’s products perform pretty damn well.

Astell & Kern are a marketing company that make some good hardware and some bad hardware. Style is as important as anything else to their bottom line, to their product line, and to their customers.

I find as few cross points between A&K’s and iBasso’s customers as I find in their product line. And the beefy, style-be-damned DX90 is the gaming rig next to the AK Jr’s style-is-all Vaio or some other non-Apple design computer.

That said:

DX90 and Jr:

– hiss: similar levels of hiss
storage: DX90 – 8GB; AK Jr – 64GB. No contest.
– battery life: a slight edge to the AK Jr but both are bad.
– sound signature: DX90 – cooler and more neutral; AK Jr – warmer and more musclier.
– output quality: DX90 – lower distortion, less load effect; AK Jr – higher dynamic range. Not a tie, and both are very good, but DX90 may be the more complete all-in-one device that doesn’t need an amp.
– outputs: DX90 has an amp-decoupled line output, and coaxial out. Jr makes do with a single, amp-coupled line output. DX90 FTW.
– in the hand: DX90 hurts less, but its horrible button placement, thickness, and small tough targets, make it a bugger to use. Jr could do with rounder edges.
UI: even tied down by adolescent firmware, AK Jr is much nicer to use, funner, and classier.

I don’t like running comparisons in dedicated reviews, but since many readers (and Lieven) have begged me to add this section, I’ve done just that, but in Nathan style.

That said, if I Nathan had to spend his 500$ on a single player, it would be the AK Jr. While its GUI needs serious update, it is so much more polished. Sussing its interface is quick, and both its software and hardware buttons fall under the finger more ergonomically.

And while I dislike its sharp edges, its stylistic ethos is easier to suss. Both units are designed poorly for human interaction, but AK Jr is less bad.

Finally, while I appreciate enthusiast-level products, my money always goes to the artisan. Again, while I disagree with the AK Jr’s design ethos, at least Astell & Kern have got behind one.

For the enthusiast wanting the best output and functionality, DX90 it is, hands down. For the portable music listener that doesn’t want to fiddle as much, AK Jr is just that much closer to a full autonomous product.

But who am I to spend your money?

End Words

Jr lacks some of the functionality (optical output) of the AK100 and AK120 it has replaced. Its corners are stupidly sharp, its screen larger, but no more accurate. Its GUI is easier to navigate, but with a battery life that tops out at around 8 hours, it won’t carry the modern work day through.

Jr has a few serious design flaws. But, in my opinion, it is A&K’s best current portable DAP. It is slimmer, lighter, and less arbitrarily designed than either the AK240 or the AK380. And it’s less expensive and has a more straightforward UI than both the AK100ii and AK120ii.

The pudding on the pie is its rocking of Wolfson’s wonderful WM8740 DAC, plugging  a niche that’s been empty since 2013.

Which means the following: I love the AK Jr. And I hate that it misses a few things.

3.9/5 - (71 votes)

Back before he became the main photographer for bunches of audio magazines and stuff, Nathan was fiddling with pretty cool audio gear all day long at TouchMyApps. He loves Depeche Mode, trance, colonial hip-hop, and raisins. Sometimes, he gets to listening. Sometimes, he gets to shooting. Usually he's got a smile on his face. Always, he's got a whisky in his prehensile grip.


  • Reply August 4, 2015


    How would you compare the AK Jr to FiiO X5II?

    • Reply August 4, 2015


      Nathan doesn’t have the Fiio, sorry

      • Reply November 16, 2018


        Any chance of having AK jr compared with Fiio X5III? Only sound quality matter here.I am looking to replace my old X5iii and get a cheaper AK Jr in its place.

    • Reply August 4, 2015


      I can answer that! I’ll stay away from aesthetics because if you want features and big size, Fiio. Less features and a slim profile with a different design? JR. As for sound, I find that the X5ii seems to be more spacious with a bit more detail on the top end (may be an impedance issue for me), while the JR has a deeper low end and while it doesn’t impress at first listen like the X5ii, I still enjoy the more I listen to it.

    • Reply August 5, 2015

      ohm image

      Don’t own the X5II. And I don’t see them as even comparable. Again, read what I said about the DX90. Fiio and iBasso are targeting the same market; AK are targeting someone else.

      You need to know what YOU want before you compare two incompatible devices.

  • Reply August 4, 2015



    I’m looking for a portable audio rig that betters my iPod touch by a good margin but I’m confused b/w the Jr and dx90.

    I will be using my PM3 and m100 with the DAP so the amp section of the DAP should provide more than enough power for these headphones.

    Music:mainly rock and EDM plus some mainstream music. Classic rock bands like pink floyd, the Who etc.

    Sound quality takes top priority everything else comes second.

    Or should I go for the Oppo HA2 and use that with my iThings and android phone. This will be less portable but as I said sound qaulity is top priority.

    Does the oppo ha2 have a better and more powerful amp than the perviously mentioned DAP’s?

    • Reply August 4, 2015


      I will let Nathan reply but I just want to point out it might not be the smartest way to go to invest in a discontinued DX90

      • Reply August 4, 2015


        Thanks L.

        I was just about to post the same question to you in the dx50 and dx90 article.

        Any thoughts on what would provide better audio performace, the Jr or the Oppo Ha2 combo?

        • Reply August 4, 2015


          Best to ask Nathan as I don’t have the Jr or Ha2 😉

        • Reply August 5, 2015

          ohm image

          I’m not a big portable amp lover. I review amps on their own merit and against other amps. But if a DAP has a decent/good enough (proper current to the right volume) output for the headphones you are using, that DAP should outperform the amp in all metrics apart from absolute volume.

          And Jr’s current is VERY good to all volume levels. And again, it doesn’t hiss. HA-2 is awesome. But I’d not put it ahead of Jr for absolutely sound quality.

          • Reply August 5, 2015


            Thank You.

      • Reply October 3, 2015


        i will ride my DX90 till the wheels fall off. A&K Jr may have the sound to rival my DX90, but the DX90 read 128GB MSD card with no issue, and battery life is improved. especially with new software. I think the sound of each device is also a big factor is which to purchase. Discontinued it maybe but a good audio products stick around.

    • Reply August 5, 2015

      ohm image

      The HA-2 can be more powerful than the AK Jr, but it is also more powerful than is necessary for the PM3. Unless you want to damage your hearing, even the iPod touch is powerful enough. The Jr is perfect.

      That said, it comes down to how you want to hear: neutral or warm. The Jr is warmer than the DX90. But the differences aren’t night and day. It is more of a patina.

      One thing to note: the HA-2 will hiss with earphones. It won’t hiss with the PM3 and M100.

      • Reply August 5, 2015


        Thank You.

  • Reply August 5, 2015


    Loved every line of this review, Nathan. I’ve had my Jr about two weeks now and despite its flaws, they (very mostly) melt away as soon as the music starts. I just sent off my old pair of GR10s to Grado yesterday for a patch-up – I can’t wait to try them with the Jr when I get them back in a few weeks time!

    • Reply August 6, 2015

      ohm image

      When they return, do update us. I love the combo to bits.

      • Reply August 6, 2015


        i absolutely will. I’m liking the AK Jr + W30 right now. I was a little underwhelmed when I used my IE800 though.

        • Reply August 6, 2015

          ohm image

          The Jr drives the IE800 perfectly, so it’s not a hardware mismatch. But when personal preferences come into play, I think it could be said that the IE800 is perhaps a bit too warm for an already warm player. But that will stand for some people. Others may love the combination.

          • Reply August 6, 2015


            I think you’ve hit the nail on the head. I did a little eq’ing to get them sounding more to my tastes when using the jr as a DAC for my MacBook Pro.

            Just as an aside – do you have any thoughts on the GR10e’s? Specifically in comparison with the GR10s?

            • Reply August 6, 2015

              ohm image

              I do not have the GR10e, I’m sorry. But the regular old GR10 pleases me so much I can’t imagine how an ‘e’ version would improve upon it.

      • Reply August 23, 2015


        Hey – thought I’d give you an update now I have my repaired GR10s. In fact, it looks like Grado refitted them as GR10e’s as that’s what they look like now; they have the bronze housing for the nozzle.

        Soundwise, the synergy between my new GR10s and the Jr is phenomenal. I’m remembering just how much I loved the midrange on them and they bring a certain ethereal quality to certain genres. They’re giving my K3003’s + AK Jr combo a run for their money. I still can’t believe that this sound comes from a single driver IEM.

    • Reply August 6, 2015

      ohm image

      Finally, thank you for the kind words.

      • Reply August 6, 2015


        No problem! I’m really enjoying reading the website and look forward to more great reviews.

  • Reply November 1, 2015

    Michael J. White

    got my ak jr a couple of weeks ago and the quirks of it ARE absolutely negated by the music quality, and that’s what’s what i was seeking. as i was unable to synch my ak jr to my deftech symphony 1 (wireless) headphones, i thought if i’m going ‘wired’, wtf, lets look at some different cans. i got the oppo pm3’s and what a combo! wow!!

  • Reply November 3, 2015


    Great review. If you were already the owner of an ak100 and you were going to spend $500 to upgrade your dap, would you go for the msak100 upgrade or go for the ak jr. ? Based mainly on SQ.

    • Reply December 3, 2015

      ohm image

      The MSAK100 is objectively a better performer. But the difference between the two is small. Therefore, based on SQ alone, the MS-AK100 is better. It also feels better in the sound.

  • Reply August 26, 2016


    Absolutely love this player! Just one large nit pick! The gaps between tracks really takes away from the overall experience of some albums. Anybody aware of how to prevent this???

  • Reply October 10, 2016


    Hi guys,
    can you give me please an advice?
    which combination to buy in terms of sound quality and maybe money:
    AK Jr. (249 Euro), Ibasso DX80(340 Euro), ATH-IM03 (249 Euro)

    AK Jr. + ATH-IM03 (or maybe with ATH-IM02, so that combo will be cheaper)
    Ibasso DX80 + ATH-IM03


    • Reply October 11, 2016

      ohm image

      Hello Tomas,

      I have only heard the DX80 at shows, and only briefly, but I remember it hissing like mad. If that has been fixed, then good on iBasso. If not, it is worthless for portable earphones. The Jr doesn’t hiss nearly as badly.

      On that function alone, I am hard pressed to recommend the DX80.

      • Reply October 14, 2016


        Hello Ohm Image,

        Thank you for you reply.

  • Reply May 3, 2017


    I wish I knew what dry warmth was.

  • Reply April 30, 2018


    Hello everybody,
    I was trying to find the equalizer in Jr but failed. Could you please tell me how to get to EQ in options?

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