About Myself: (I can review anything, if I am provided with the product :p)
Intro: The AK100 isn't a new product, but I've been noticing interesting trends on head-fi to either hate or love the AK100. So, I though I might aw well share my opinions.
iRiver decided to dive into the audiophile market by the name of Astell&Kern. I think AK was originally another company, but iRiver bought it off. iRiver was already known for great DAPs, but with the eye opening MSRP of $699 USD, took an entirely new approach to the DAP market. In a way, I praise iRiver for starting off the audiophile DAP market. Of course, there was DX100 and C4, but nothing quite as sexy or user friendly as the AK100 was out in the market.
AK100 and Shure SRH940
The main selling point of AK100 was the WM8740 DAC along with the capability to play what iRiver called MQS music, for lossless files with 24bit resolution. Us audiophiles always had discussions about whether difference between 16bit and 24bit is noticeable, but speaking in terms of the specs, there definitely is a difference here. For non audiophiles(although I don't know why any non audiophiles will read this), let me try to explain this. Normal 16/44.1 music files have the frequency extension of about 16k, which is adequate for most people. According to iRiver, 24bit files have extension of about 50k, way beyond human hearing. Everyone has different hearing extension, and researches show incoherence when it comes to the extent of human hearing. I've tested up to 20k myself. Most headphones can't even reach 20k.
OK. Enough of my opinions. Lets look at the datas. This is from Astell and Kern's website.
So, lets go over all this.
DAC: Spectacular. I love Wolfson DACs.
Output Level: Hmmm.... for amp users, this means that the output is attenuated.
Channel Separation: Superb!
THD: OK. This is good. Really good.
S/N: 110db is good. It should be really black and silent.
Jitter: IDK. I really don't know much about the jitter clock.
Outout Impedance: WTF. Here we go. Now we find the issue here. 20ohm output.... I'll cover this later.
Dimension: It's really small and compact.
Sample MQS Album
No IEMs are included.
Sweet and clean. It looks modern and simplistic.
Overall really really good. In fact, AK100 is the most strongly built electronic device I've held up to date. Comparable to the famous Nokia phones. I've dropped them on concrete road, wooden floor, carpet, you name it. It is yet to fail me. It feels really solid, and it is. Made of all aluminum and crafted in Korea, expect master craftsmanship. The volume wheel feels flimsy and wiggly, but it's attached inside by a metal pole, so do not worry. The wheels are as steady as they are ever going to get. The wheels also feel really good.
The pouch included is thin and pointless for portable usage. I suggest you get a nice Dignis Case.
Solid 32gb storage. It's quick to copy files on to AK100.
Micro SD Cards:
AK100 allows two micro SD cards. I've only tested up to 32gb, but other head-fiers have tried up to 128gb(per card). This is heavenly, especially if you load lossless files.
The volume wheel is so fun to play with, but practical at the same time. You can also adjust the volume with the touch screen, if you want to change the volume quickly.
The screens are bright and clear. Maybe not as clear as phones nowadays, but it's pretty good for a DAP. It's responsive and works like it should.
UI is good. It's not like an modern android, but it's good for a DAP. Much better then Fiio X3, which I had a chance to try at Korea.
It takes AK100 some time to refresh it's media library. However, AK100 allows the user to manage playlist or even delete files on the player. One complaint I have is the lack of search feature.
With the newer firmwares, AK100 started supporting USB DAC feature. This means that you can use the AK100 as a USB DAC! It doesn't like to work with USB 3.0 ports, so make sure your computer has a 2.0 port. But overall, USB DAC sounds superb, and supports up to 24/192 files. AK100 also has an optical input, and hence can be used as an optical DAC as well, and optical DAC sounds superb as well.
Not only does the AK100 have an optical input, it also has an output! The 3.5mm hp out doubles as an optical output, meaning if you have a summit-fi DAC or other DACs, you can use the AK100 as a media server.
Infamous output impedance and the amp performance
I am convinced that AK100 is meant to be for full sized headphones and dynamic IEMs. Output impedance is about 22ohms, which is annoying. High output impedance may alter the sound signature of an receiver. The affect of high output impedance depends on the receiver, and I can't tell you how it's going to be until I've tried the pairing myself. To give a quick reference, most portable amps have output impedance below 5ohms. Most audiophiles like output impedance below 1ohm. However, don't let this let you down completely. Some receivers aren't affected by the output impedance, and some actually benefit from high output impedance. You may also use an amp to negate the high output impedance.
AK100 provides good amount of power. With the additional 3db boost that iRiver implemented, the AK100 provides enough power for all my headphones, including SRH940 and KEF M500. However, I don't recommend that you use a headphone with 300ohm+ impedance with AK100 without an amp.
While silent(no hiss) enough for all iems and portable headphones, the high impedance output messes with the sound signature of portables headphones and iems. Here are few portable headphones and IEMs I've tried with AK100 and thought paired really well together.
Sony MDR7550, EX1000
KEF M500(kind of skeptical about this paring though)
Now the sound
Leckerton Audio UHA-6S.MKII
Ultimate Ears UERM
Shure SRH940, SRH1540
Bass is liquid and punchy. AK100 is flat, but expect full deep bass extension. However, with harder to drive headphones, the bass might lack impact when compared to an amped set up. For example, SRH1540 gains more punch when paired with UHA-6S.MKII.
Buttery smooth and rich. Detailed and clear. Some say AK100's mids are recessed while some say that it's rich. I tend to stick with the rich approach. The mids are very fluid and full sounding. It sounds intimate, but really clear at the same time. Reminds me a little bit of SE535's mid approach. Intimate and rich, yet very fluid and clear.
Fully extended and present. AK100 is really smooth overall, and treble is silky and sparkly.
Very well detailed and accurate.
AK100 is fast in decay and true to source.
I prefer AK100's DAC to Modi. I think AK100 is much more natural with better imaging and smoothness.
I prefer AK100 to X3. X3 has more power, but AK100 is just much more articulate and emotional.
UHA-6S.MKII ties with AK100. Amp section of UHA-6S.MKII rates higher, but I rate AK100's DAC higher.
Conclusion and Complains:
Do I think AK100 is good? Yes. I think that AK100 is a wonderful device for audiophiles. However, when I see my friends trying to buy AK100, I want to stop them. Before buying the AK100, I say you must know exactly what you are doing.
Before buying the AK100, check these:
1. Do you have a good iem or a headphones? I don't mean beats or anything. I mean something seriously audiophile.
2. Do you know if your receiver matches with AK100? This is tricky because of high output impedance.
3. Do you know that AK100 isn't going to magically improve crappy music? Don't expect magic. When audiophiles say day and night difference, they mean that it's barely noticeable, but noticeable.
4. Do you have high quality recording to match the quality of AK100? No 128k mp3 files please. At least 320k and lossless.
Here is my few complaints.
1. Lack of search feature.
2. Media library refresh: it take freakin 10min
3. 22ohm output impedance.
4. Lack of true line out.
So, as I mentioned above, 22ohm output impedance and lack of line out not only bother me, but bothered other users as well. Hence, Vinnie of Red Wine Audio decided to do some mods for the AK100.
Here are mods he offer:
Gets rid of the 22ohm resistors, hence resulting in a clearer sound and better compatibility with IEMs. As much as I would like to write my own opinions on them, I don't have a RWAK100(Sorry. I'm broke). $250
Vinnie did it! He pulls out the WM8740 and replace it with the WM8741 chip. The amp is removed as well, so you can only use your AK100 as a DAC. $495
However, if these prices are too high, you can just pair your AK100 with an amp to cancel out the output impedance. Just set your AK100's volume to max, and use the headphone out as the line out.
There is also the AK100 MKII, which is the same as AK100, but with lower output impedance(<3ohms).
I thought I may as well write this up, with all the new Ibasso and Fiio DAPs coming out.
Edited by kimvictor - 3/1/14 at 2:14pm