Us headphone enthusiasts strive to find the best combo of source, DACs and amps on the go so that we can make our headphones or IEMs sound the best they can but some times these rigs are just to big and not portable enough and that is why I have started taking an interest in high end DAPs (digital audio players) that intend to include a high end DAC and amp all in one parcel. However some of these players are actually just as large as stacks I have made with the HiFi ET MA9 sounding great but having an abysmal UI, lack of ergonomics and a stupendous weight and the iBasso DX100 has some similar problems as well, size being a big factor. When I saw the iRiver AK100 my eyes lit up because quite simply, it was small, plays hi-res files, seems to have nice ergonomics and utilises the amazing Wolfson WM8740 DAC, something that was made with more desktop stuff in mind and not portable use. Obviously this is not going to be as cheap as your Apple iPod and it has a price tag of £550 over here in the UK that slots it in a little under the DX100 and very much similar to the MA9 and Colorfly C4.

The Good


I think this device looks beautiful. The front and sides is black brushed aluminium and the back has a layer of protective glass. Edges are rounded and then you have the perhaps over sized volume knob on the side that actually is a joy to use! Physical buttons are kept to a minimum with a standby button positioned much like an iPhone lock button and three circular buttons on the left side that work much like a inline remote on a headphone does, pause/play, next/ back, you know the drill. While my MA9 looks like an ugly block of metal, the AK100 looks like piece of art and something that should have a premium cost, it seems that they have spent time designing it and it pays off. Oh and did I mention that there are also silver and gold versions of the AK100 if you would like a bit of bling bling!

Build Quality:

No, it is not as solid as what was once named the indestructible player, the MA9, but with a combination of aluminium and glass chassis it is something that both feels great and should last a long time if properly looked after. Talking of it being properly looked after, the package includes some screen protectors and some back protectors and you can also get iRivers very stylish leather case made with the AK100 in mind. The only real niggle that I have is that the volume knob is a bit loose and hangs out a bit from the device making it a target.


I am very glad that I can say this is good as although I put sound quality as my number one priority, having something that is easy to use is always a huge bonus. The action happens on the 2.4 inch touch screen that does not boast retina display or full HD but looks nice enough. After the boot up that takes roughly 30 seconds you are launched straight into the music player with the album artwork showing and song information on the screen. From there you can go into options with a click at the bottom right and in here you have the equalizer, the option to add to a playlist, information like bit rate and sample rate of the song and then the shuffle and repeat settings.

Playlists are awkward to create and you have to add song one at a time but with playlists not being something I use it was not a hindrance to me. The other option you could take from the music player is to the ‘music list’ with a click to the bottom left of the screen. This is displayed as a list as you may expec and in here you can navigate through your music in the standard ways an iPod would give you (artist, album, genre, playlist, all songs) and you also have the settings of the device it self such as date and time, display and power and also some advanced settings. There is some lag but I am only talking 1-2 seconds when asking it too do something and never have I got frustrated with it; most of the time it is quicker than that.

You then have the volume that is controlled with the wheel on the side and that moves it up in 0.5 increments from 0 to 75 and you can also use the touch screen to make large jumps. It is a very enjoyable process and is very accurate.

The only part that is rubbish is the battery life indicator that does not work (jumps up and down with no real aim) and should never be trusted, which is a real shame.

24/192 Support:

Being able to support 24 bit files and up 192 kHz sampling rates is a big thing these days as a lot of people are wanting the best formatted music to start with and too right as it sounds great. There is also a lot of places to buy it online now with the likes of HD Tracks having a huge range.

Size Against Competitors:

 iPhone 4


Colorfly C4

iPod Classic


This has a huge potential in terms of how much storage you can reach with this. To start with you have 32gb of internal memory that is a decent amount and will give you a nice amount of songs, differing of course, with what type of music you use. You then have two, yes TWO, micro SD card slots with both accepting 64gb cards you can get too a massive 160gb and also have spare cards on you that moves you up to a hell of a lot of music.

Battery life:

The official specifications say that this will last 16 hours under certain circumstances but lets face it, you will never reach that but from an average full charge that takes 5 hours, but I do ooze 10 hours out of this baby and that is all I ever need. I use it for a few days and then it charges over night and I never see the out of battery screen.


The AK100 makes use of both an optical input and output and combined they work out very handy. I personally am a big fan of the optical output so I can use the AK100 as a small digital transport with a nice UI. At the London Head Fi meet it was a great way for people to demo my Rein Audio X3-DAC and Violetric V200 and I must say that I find the optical output to be of great quality, mini-toslink is certainly getting better. It is also really handy with portable DACs such as my MyST PortaDAC, with the AK100s great size this makes a deadly combo. There are also some more ergonomic combinations such as a model from xDuuo that was made FOR the AK100 using the same Wolfson WM8740 DAC and just a less problematic amp.

You then also have an optical input that I guess is a nice feature but not one that I tend to find a real use for. I did try it out using the optical out of the Marantz CD94 and feeding it into the AK100 and then simply using the headphone out of the AK100. However I have dedicated desktop gear such as the Rein Audio X3-DAC that sounds a hell of a lot better than the one the AK100 has and I do not see the point of using the AK100 over it. However if you do not have any dedicated desktop stuff it could be really handy.


It first of all has EQ that is always a plus but it is also very usable. You can draw curves your self-using the touch screen on the 5 band equaliser and you have 10 decibels up and down in each of the bands that allows a lot of space to play around. I did find the EQ to work quite nicely and not have negative effects on the sound. I am not one to really judge EQ however as I scarcely use it. The only bit that is not great about the EQ is not already made presets like bassy, radio, rock, jazz etc. and there is only user mode.

Sound Quality Technichalites:

From a technical point, the AK100 really does impress. The frequency response is very flat to start with. When paired with a headphone that this suited you get a very honest representation of what it can do, no added warmth, not treble happy and just how it should sound. Roll of either end is also very minimal, we do not lose any deep bass and if the headphone is capable of endless and airy treble the AK100 allows it to be just this. Perhaps my favourite part of the AK100 is how black the background is. It is dead silent, not interfering the slightest with music and it rivals that of top DACs like the Rein Audio X3-DAC. On top of these things we also have low distortion, I never got the hint of any and also great dynamics. Everything is fast with strong impact and really throws things around. Soundstage is also very nice; I think it slightly out does the HiFi ET MA9 but certainly not the Colorfly C4pro. There is no doubt that is does some great sounding stuff but I would recommend you read on because not all is so good.


This can scrap all objective ideas of what should happen and for some reason pair just beautifully with some earphones. This was my favourite pairing with the Tralucent 1plus2 and Lear LCM-5 out of all my portable gear. I almost feel like this has a rather special knack of finding synergies and them being especially good ones. They seriously blow your socks of and if you do find one you will be in sonic paradise.

 The Bad


I really do not see the point of this as well as the fact that, well it does not work for the purpose I would expect. I booted up the Bluetooth modes on both my MyST PortaDAC 1866 and Jabra Solemate and expected the AK100 to find them so that I can use Bluetooth as a digital audio output. Well it does not find them or connect with them so it has no Bluetooth audio output and it could connect with my iMac but for no real purpose, it did not seem to want to do file sharing and that would take forever with high resolution music and would give no reason to not just reach for the USB cable instead. It seems it has this Bluetooth mode for no real purpose and I think that is a bit stupid.

Line Out:

I know iRiver have been saying that the headphone out when maxxed out on top volume is pretty much a true line out but it isn’t and it is clear that it isn’t. For a start when using an external amp the volume adjustments are really bad because the volume on the AK100 is maxxed out and this is instantly awkward, with you not having a lot of room to adjust volume and the sound instantly getting very loud. Also it does not work very nicely with a few amps I have used, the line out of the MA9 is so much cleaner for example. They have given another 3.5mm jack on the top for the pointless optical input so why not give another one to a really handy line out? It is beyond me why they have done this and quite frustrating.

Driving Ability:

The AK100 really lacks the power to drive any headphones I have tried with an impedance of over 150 ohms. This is quite a sad thing as the DX100 can drive most headphones very well and although this could get both my Sennheiser HD580s and HiFiMAN HE-500s loud enough, it heavily lacked the dynamics and punch to make it enjoyable. Considering driving headphones is something that iRiver go on about and give it as one of the reasons for the high impedance output, it should really do a lot better.


They did not implement gapless playback in this and this is quite a huge thing considering it should not be hard to do but is quite a needed feature in something that costs almost 600 pounds. My much cheaper Nexus 7 can manage it as well as be used for a lot of other things and so can all the other contender DAPs so I think it really is not acceptable that this does not have it. The delay really gets annoying and while I won’t call it deal breaking, I know others will! What I mean here is that after a song finished you get a pause and small click before then next song plays when it should move on smoothly and instantly. (FIXED IN FIRMWARE UPDATE)

22 Ohms Output Impedance

What is this?:

Almost just almost this player came in nearly flawless but it has a problem in the amp section that is perhaps unforgivable. The output impedance of the amplifier stage is 22 ohms and this is the cause of some very serious problems. Due to the effects of damping it is a rule of thumb that your earphone should have an impedance of roughly 8x the output impedance of the player, meaning ideally this should not be used with anything with impedance lower than 176 ohms. An effect of this is an obvious drop off of bass, reducing some headphones to something that is completely bass-less.

You also have the effects on frequency response, because a lot of headphones do not have flat impedance plots, especially multi armature IEMs with crossovers that can be quite all over the place, the high output impedance coming from the AK100 means less voltage enters the earphones and this makes the different frequencies get a significant amount of difference in volume resulting in a obvious colouration and screwed up frequency response. It is noticeably different and you will be able to tell what the measurements confirm.

Bad Experiences:

My most obvious example is probably with the Beyerdynamic Custom One Pro headphone, which has 16 ohms impedance. This headphone has tuneable bass and can get to a point where bass monster would be how I would describe it. With the AK100 and the Beyer’s bass port fully open I could hardly feel any bass let alone feel any, it was an anaemic experience and was not acceptable.

When I first received the Rhapsodio R^2 I was using the AK100 a lot so the first thing I did was plug them into the AK100. They are dual dynamic IEMs and I expected them to be really bassy and what I got was little to no bass but a lot of sharp, sibilant treble. I am now using them with the iPod Classic and JL Acoustics Balanced amp and I can tell you they have a rather balanced sound signature with very powerful dynamic bass and have a very pleasant treble that is the slightest bit sharp but nothing like the AK100 emphasised.

Then you have the Cosmic Ears MA2 that now sounds like its midrange is washed out and the bass is a bit lighter. It sounds murky and claustrophobic, not the IEM I am a big fan of at all.

I have to be honest and say that most experiences were bad and it could also lead to some bad experiences with earphones that are actually really good if this your only player. I mean if you’re an AK100 owner and bought a Rhapsodio R^2 you may not think much of it but I can you now it is AMAZING!

Good experiences:

Tralucent 1plus2, I did not hear them to be coloured in anyway and the bass was just as dynamic and powerful as with any other source, no problems here at all and I loved using this pairing.

Lear LCM-5, I think we do get a slight warmth added and a bit more bass likely caused by the low impedance and three way crossover but the changes made left me really enjoying the earphones, more than ever in fact.

Heir Audio Tzar 90, this was made with the AK100 in mind and has 90 ohms impedance that is fairly high but still not ideal but better than most IEMs. The sound was punchy and dynamic and better than with the HiFi ET MA9 or iPod Classic/Lear FSM-02 V2 combo.

MyST Nail 1 V2 and Nail2 V2 have 60 and 120 ohms impedance respectfully and they sounded AMAZING with the AK100. Beautiful bass, no extra colouration and a dead silent background, could not ask for more.

Westone 4 managed to sound no different than normal with good punchy bass and clear mids and treble.

There were some good and ones and also some that were just magic and with these pairings you do get too see how good the AK100 actually is. If you get a good pairing your in for a real treat! I was just plagued with a lot more negative ones when piling through my collection.


The high output impedance is for them to work well with hard to drive gear (or so they say) but I have found it to do very poorly these types of headphones (hard to drive) and there is also the point that when something has such an amazing form factor and great portability, I do not want to use it with my hard to drive open backed headphones but just on the go with easy to drive closed headphones or IEMs. The size is one of it most sellable points so why not make it perfect for IEMs but the output impedance stops that dead in its tracks, simply because you can not guarantee you will get a good performance at all unless it is one of the 4 high impedance IEMs out there, the Heir Audio Tzar series and the MyST Nail series meaning that this is only really compatible, with 4 earphones statistically.

So high output impedance for hard to drive headphones > Not enough power for hard to drive stuff > high output impedance rubbish for IEMs = a vicious circle.


Fortunately some people with better knowledge of the inner workings of devices like these opened one up and have found it not the most difficult operation to bypass the 22 ohm resistor causing all of these problems. The first company to do it was Red Wine Audio with their well-named RWAK100. They are already well regarded for their iPod modifications and there desktop amplifiers among other audio products. For the service they charge 250 USD if you supply a AK100 or 900 USD for a unit already modified and for that they simply lower the output impedance to an ideal < 1ohm. There is also an Indonesian fellow who enjoys the hobby but also does a modification with a range of high quality wire and although he cannot do a lot and is not a company, he can be found through head fi and you may use his services. Lastly Thai Mezzo hifi also do a version, again with a different cable for a different sound and they also lower it too less than one ohm output impedance. Sadly no one offers this in the UK just yet but Red Wine and Mezzo are willing to ship to the UK. It should be noted you lose your warranty if you have your AK100 modified but it seems to be worth it and Red Wine will give you a warranty with there service. I hope to try one of these modified versions in the future.

Secondly there is the AK120, a new flagship DAP from iRiver that has just been announced. It will be a fair bit more expensive but has two DACs, gapless playback, can be used as a USB DAC and now an output impedance of 3 ohms. I will be reviewing the AK120 soon so watch out for that.


So Close:

The whole experience with the AK100 has been a love hate one. I fell in love with the portability and UI in comparison to its competitors from the off, even if the lack of gapless annoyed me but I found it just so frustrating to find a good pairing because when it was bad, it really was bad. For a device that should be an IEMs perfect companion, it is clearly. So nearly did they blow away all the competition but they missed the prize on this one. However I do think the AK120 could do special things and I cannot wait to see how that fares so stay tuned!

Sonny Trigg