Acoustic Research AR-M2 DAP


Before I start, I would just like to start off introducing myself.
The review is subjective and without knowing the person, you can be led to reach a completely different conclusion.
This will not be a full feature review, if you want to know what it is or the component used, stop reading.
*New additional update has been added at the bottom. (26/02/2017)
Self Introduction:
I am a new audiophile, living in Hong Kong.
Hong Kong is extremely popular with audio products, especially high end IEMs and DAPS.
We also get some of the newest toys around, so YAY Hong Kong!
I mostly listen music in FLAC format. I cannot tell the difference between 16 bit and 24bit audio, so I do not have a golden ear for sure but surely will know which is a good recording and which isn't.  
My music collections are mostly movie sound track such as Hans Zimmer and Japanese Pop and some metal such as System of a Down.
And I am not a native English user, so please bear with me. 
Anyway, gear that I currently own:
V-MODA Crossfade M-100 (which I dislike)
Philips L2 (which I love a lot)
Nuforce HEM6 (My favorite IEM at all time)
Oppo HA-2 
Audeze EL-8 open 
And of cause AR-M2 (almost a week use now)
Look and physical design:
This is one of the best looking DAP in the market imo, just have a look at the photos I took at below. 
I definitly prefer this look than the AK brand DAPs. 
It's clean and mature designed.
It is slightly heavier than a smart phone (I am guessing around 1.4x a LG G4)
The weight gives off a very premium build quality, something that a watch lover would love and appreciate.
The back has a very nice texture polishing, holding it in hand feels incredible. So good that I am not thinking to get a case at all. 
It is thick, but notice the slight curve on the back, having this in the pocket feels comfortable.
Anyone who owned a sony Xperia phone would know how a sharp edge rectangle phone is a big annoyance in the pocket. 
Onto the functionality, there are all the essential physical button. Nothing to rave about but something worth pointing out when comparing against the smaller brother, the M20. The M20 cut down quite a few of the dials.
My only complain is that the buttons are slightly too far apart, a bit hard to use one handed. Which is a shame because one of most important button for me is the fast forward button, and it is quite far down for me. 
If AR is reading this, put everything closer and add something to the play/pause button so that it can be easily identified and used in dark environment.
Other notable points:
1. You can only fit one micro SDXC card inside, the DAP itself has build in usable 55.6GB. I wish it was larger because while it is expandable by the use of micro SDXC, in my experience that is never going to be as efficient as simply having a larger build in storage.
2. The SDXC slot door looks terrible, but I find almost all DAP doesn't know how to make it look nice. There is no lock mechanism and is very loose.
3. WiFi works 
4. The system is VERY responsive, probably due to the very clean and customised android. I am extremely impressed here because navigating is silky smooth.
5. Drag and Drop, extremely easy to handle.
6. Monitor is very bright, too bright in lowest setting imo.
7. Battery life : roughly 6 to 7 hours.
8. The volume dial is extremely smooth
Audio experience:
The Audio Quality imo is super good, the difference between FLAC and spotify high quality is actually noticeable.  
If you are purchasing a high end DAP, I don't think I would be dissatisfaction with any of them though.
I tested out against:
- Onkyo DP-X1
- Fiio X7 with AM2 
- AK 70
That is with the store's pick of music, so I could not do a AB test and because of that, just take this as a grain of salt. 
The ARM2 sounds more lively and just overall more of my liking in many genre of music.
I wouldn't say it is a HUGE win for AR-M2 but I suspect for certain type of audiophile music, it can be pretty significant. 
The actual performance difference for me is the driving power.
Let's just say it was eye opening, it is far more powerful than Oppo HA-2 even with high gain.
I tested out with several big cans and below is the result: 
HE560 (OK)
Hifiman edition X (EASY)
Oppo PM2 and PM3 (EASY)
Nighthawk (EASY)
Focal Elear (EASY)
The only difficult headphone to drive was really just the HE560, but it is totally at a reasonably GOOD listening volume at max setting.
In fact I suspect if the guy next to me won't blasting music via the bluetooth speaker, I would have enough room to actually adjust the volume.
Now that I have a EL8 Open, I can drive it with Oppo HA2 to high gain and it can be slightly too loud. But if I use my AR M2 and put it on max? The headphone is basically a speaker.
And the biggest improvement is the L2. the difference is pretty massive, almost sounded like another headphone entirely. 
The Flaws:
No device is perfect and so here goes, AR-M2 is far from perfect.
Below is some of the more major "flaw" that warrants a mentioning:
1. This DAP is designed more for headphones, particularly full sized/ harder to drive set.
Adjusting the volume causes noise, and I read that you can also get noise from the wifi and using the monitor. Apparently this is caused by the strong AMP.
For me personally, I only have noise for using my L2, M100 and HEM6 when I adjust the volume.
I get very little noise when using the EL8, the EL8 for me is a perfect match with this DAP.
2. Pop when resuming play. Not terrible but over time it does get annoying. 
3. No way to tell the volume until you listen to music. This is also quite an annoyance. Imagine I turn up the volume when listening to EL8, and going back to HEM6 to listen in bed, the volume is way too loud and there is no way to tell.
I think this is one of the happier purchase in recent year and I have made a LOT of expensive purchase. 
The flaw is completely overwhelmed by the awesome listening experience but they are there every single time it happens which does build up.
imo, it is slightly expensive for the original cost, but if I am happy with this purchase, I am sure a true audiophile will be even more impressed than I am.
But when I listen to my fav songs at this high quality, I can't help but to close my eyes and smile a little.
------------------------UPDATE (26/02/2017)-------------------------------
I would just like to add a small update just to ensure every detail is here and updated.
The goods/ improved/ additional positive comments:
The new addition - Gapless play works perfectly.
No more bugs or pops! 
Classical music imo is the genre that shines the most. I tested it out with HD650 and the sound stage is unbelievably large and full with precision.
The bads/ hope to improve/ additional negative comments:
The music commands have small lags after the update.
The storage space is not enough, high res music takes up storage space pretty quickly and I already have a 256GB additional storage in.
I am using it more and more as a bed side set up. 
Reason being is that I only really have 20 mins of travel time to work per day and I don't need the highest of quality for music playback.
The sound quality is so good that I actually am looking for a desktop set up to match this level of performance 
Great review enjoyed reading it very interesting.
Does it still have noise while using wifi or other app?
did you experience warm on unit body after use it a good 20-30 minutes?


Sponsor: Trinity Audio Engineering
Pros: Great UI, Amazing Sound, Competitive Price
Cons: No extra gubbins, Pricy for some
The Acoustic Research AR-M2
The Anticipation (Skip to the review part if you need to)
I first got the chance to hear this sleek beautiful piece of art during the Headroom Show down in London. I actually remember passing it by initially thinking I haven’t ever heard of that company before perhaps I will try it a little later. Well after trying out everything on offer and just before leaving I remembered that oh too curious, unknown shiny box.
You know what they say though save the best to last. By this time I had already had the pleasure and privilege of listening to the famous Astell&Kern AK240 married to the brand new Layla by JH Audio. So quite a winning combination, running straight from balanced mode and playing DSD files no less! Long story short I thought it was a great sounding bit of kit although, for the price I was hoping for some kind of mesmerising unheard of sound. I will say this though I still have never heard anything as coherent, refined and mature yet, so in regard to that aspect it simply was perfect.
For comparison I only had my trusted Dunu 2000 for a quick A and B test from one player to another. Recalling from memory my Dunu 2000 sounded better out of the AK240 over my iPhone 6, just not an extra £1,790 better (If you can quantify sound with a price tag). Anyway I promise this is leading somewhere, so continuing toward the end of the show feeling a little weary after the five hours spend on my feet and all the traveling I stumbled towards Sennheiser’s booth.
Now never being a huge fan of the HD700s against my better judgment I placed them over my head to hear what this magic box was doing to them. After seeing a few grinning faces I figure it’s worth a shot. WOW yep capital W.O.Ws I simply hadn’t heard the HD700 sound so good. Shortly after this I plugged my earphones in and just the same again stunned by the spacious clean sound being reproduced. This thing was even making my humble Dunu 2000 sound better in a few areas compared to the AK240 Layla combination I had heard prior to this. Maybe this was synergy gone mad maybe this was just plain better recordings and files who know but I know it sounded good!
After a brief chat with the product manager and a brief chat with Robert arrangements were made to have it shipped out for review when available.
The Review
So today I finally have the jewel in my hands and it is definitely an honour. I can see this being a very popular product, if given the chance with the long line of audiophile daps now available, but please if you can get your hands on it grab the opportunity.
Due to the nature of this review and product I will try and manage each section into nice bite size chunks. Focusing mainly on; Sound quality, User interface, Practicality, Functionality, Features, Power and Accessories.
For this review I will be using my Dunu 2000, Audio Technica ATH-50 (Re-cabled by Forza Audio Works using their Hybrid cable) and the Beyerdynamic T 90 using mainly Spotify all at extreme quality.  I will shed some light on the differences when using higher bit rate files which, in my opinion does give a perceptible boost to audio quality.
The Package
Although, for some this may still seem an awful lot to pay for a digital music player I do believe it is a little more reasonably priced in comparison to some of its competitors.
That being said don’t expect an array of accessories you will still get all the basics though. So what do we have inside, let us find out? Included is; A USB cable, a soft draw string pouch, a few selections of adaptors and a USB plug socket. Really not much to get excited about but hey they have certainly provided the bare essentials.
I am not too concerned with the lack of accessories, as when purchasing anything to do with audio, sound will always be my primary concern. However, even a nice leather case or a memory card could have been the cherry on top to sweeten the deal but I digress.
Below are some pics of the box accessories etc:
- 5 inch OGS HD IPS colour display screen
- Easy-to-use Multi-touch “MusicSurf” GUI 
- Android OS base, tuned for pure music
- Pure Lossless Audio Path bypassing Android OS totally
 - High capacity battery 4000 mAH - 9hrs average battery life
- Duralumin metal housing - tough and good-looking
- Dedicated line out
- Headphone out
- Easy to use play, pause and track selection buttons
- Burr-Brown PCM1794A Current Output DAC
- 64GB built-in memory plus flexible storage expansion through Micro SDXC
(Expansion Up to 200GB)  
The 64GB internal memory could be conceived as a touch limiting. Perhaps a 2.0 version could be launched in the future with an internal capacity of 128GB. Fingers crossed guys.
Full Wi-Fi streaming capability
I thought best to add a little sub section on this so as not to interfere with the rest of the review. The connectivity is great I've not experienced any problems although, I can say the range won’t be at the level of most smartphones today. Generally speaking for home use you are free to roam and still have quick access to live streaming, browsing and whatever else you like to do with your internet.
Also a nice bonus feature, with the use of a personal hot spot means, if you sync your phone and AR-M2 together you can stream anytime anywhere, which is great to have on tap if you happen to like streaming music now and then. I really have been enjoying this feature because as good as the iPhone sounds for a mobile device it certainly isn't anywhere near the level of the AR-M2 but with the hot spot it’s like having the best of both worlds. You get all the browsing time you wish and what is essentially an unlimited library at your disposal.
YouTube and browsing are all fairly nippy but YouTube sometimes takes a few moments to load even with a great connection. Surfing the web is all the same as today’s modern smartphones like a mini laptop on the go.
If I were to use an analogy this is practically a Sony Z1060/iPod touch on steroids.
High-power headphone amplifier
- Power output (THD < 0.01%)

- 32 ohms 400mW + 400 mW 

- 300 ohms 43mW + 43mW

- Ultra-low-distortion at max output <0.01%

- Supports 16 ohms to 600 ohms headphones/earphones

- Ultra high slew-rate, genuinely responsive to Hi-Res content
I am going to include driveability in this section as I feel it best suited seeming as this is the headphone amp section. The player has some serious power to give and will probably drive just about anything.
I did manage to get some testing done with Beyerdynamic’s T 90’s thanks to the guys at Richer Sounds. The AR-M2 certainly has enough power to drive them comfortably when using the inbuilt player. However, I don’t know if there is an undiscovered setting but the power certainly dropped when using Spotify causing me to crank up the volume considerably more.
Just a forewarning if you go to switch between the two remember to lower the volume gain or you may end up blowing your ears off.
The T90’s sing with the AR-M2 what was essentially a little lifeless is given new breath with this player. Everything from soundstage to coherency was simply bliss. The most noticeable improvement made, other than driveability, were the subtle details suddenly revealing themselves and the vastly improved soundstage with an added sense of space and air making you clearly aware what instrument is playing and where.
Supported File Formats
The AR-M2 plays the following audio formats (WAV, AIFF, FLAC, ALAC, APE)
Plus DSD64/DSD128 & DXD
Custom developed Hi-Res DSP processing
Upgradeable to support other new formats
I have also uploaded a link with a more in-depth write up of what the AR-M2 is all about               pricing, origin, more specs, the why and the what and so on :
Now back to the review.
User Interface
Disclaimer I haven't had the pleasure of using countless high end DAPS but I will say for usability this is by far my favourite in all those that I’ve used. Anyone who is familiar with an android or OS operating system will be able to learn and pick up the basics very quickly.
Navigation is swift and really easy to use. It is essentially a hybrid OS Android based operating system. Anyone who has used a smartphone will be able to use this device without hassle.
So far this is the most responsive DAP I have tried and I would like the chance to compare it something like the new Sony NWZ-ZX2. I have consistently switched out applications, changed songs and browsed the internet but still not even a single flinch or glitch.
This is such a contrast to say something like the Cowon Z2, no offence, which was just abysmally slow. I used to get frustrated waiting for songs to load and browsing the internet was just a joke.
I really like the interface on the AR-M2 it actually reminds me an awful lot of the Sony Z2 phone, very nippy and doesn't bug out when handling complicated commands. Now although I know thought has gone into making sure this thing doesn't overheat I will pre warn you, you will most likely feel a little warmth being dispersed when pushing it, browsing the net, running apps and especially using higher rate files.
Below I have uploaded a few pictures of the Dap’s UI:
Some of this is obviously going to be very subjective as I’ve already noticed a few unfavourable comments on the design. But to each there own I actually quite like the simple, sleek and brick like design. I know that sounds like a negative but I really like the feeling of this manly machine in my hands. This to me is a real bloke’s music player solid, rugged, thick and firm so let’s keep the comments clean. J
I do remember holding the AK240 and as innovating as the design is, which I did like by the way, I was slightly worried I might have dropped the dainty little thing. Aside from that I still find this player will be one of those marmite designs, for me I love it, actually reminds me of a hybrid iPhone 4s and iPhone 6.  Here are the official dimensions; 136.5 h x 71.1 w x 15 mm deep, with a weight of 245 grams. Not bad at all, for comparisons sake I've uploaded a picture of it next to the iPhone 6, which I’m assuming most have had a chance to see in real life.
Installation and File Transfer + Boot speed
Now on to the functionality, well it works huzza as it should. Kidding aside I think the design makes for a real functional and practical solution.
This really couldn’t be easier simply plug in your device and your computer will do the rest. There is no need for driver installation and file transfer is just a simple drag and drop. I absolutely commend this firmware implementation, a tip of the hat, it’s nice to have an audiophile dap without the typical firmware glitches that usually accompany them.
Thankfully due to the operating system everything works smoothly without any bugs I haven’t had a chance to transfer any DSD files over yet as I don’t own any but I assume there should be no issues there.
Just keeping this diminutive, from a fully shut down position boot time is about 15-20 seconds before you’re up and fully operational.
App Installation
Typically speaking if your thinking of purchasing this player it is not to play games or download a crap load of bloat ware that being said some apps maybe a vital need in my case Spotify. Installation of apps is fairly simple, initially upon receiving a new unit I had a few issues trying to download through Google play, instead of using a straight apk if you have any issues downloading any apps always try downloading the apk file first with security switched off. Once this was sorted had no problems getting what I wanted installed just download open and let it do its thing.
Volume Control & Keys
One thing I really quite like is the volume knob, don’t ask me why I just like fiddling. The volume knob is located at the top of the device simply scroll left or right to turn the volume up or down. In terms of realism it is quite useful to have it located there. It is a very smooth operator no clicks just glides from side to side, I love it as you can probably tell. But you have to be quite careful due to the lack of resistant the volume can be adjusted a little too easily.
Let’s say for example with the iPhone a song happens to pop up and it’s a little quieter or louder than the previous song I always find myself having to pull my phone out of my pocket to mess around with the volume, with this on the other hand it’s just right there on the top so without even having to faff I can safely adjust the volume to my desired volume.
Another plus for me and it baffles me why some companies did away with the play, pause and track selection buttons is just the simple convenience of having them there on the side without having to open the device. For me I can tell someone really sat down and thought ok guys what would we like form this device, what is going to be practical, and how are we going to combine the two effectively oh that’s right let’s bring back that classic bit of common sense.
That’s essentially what I feel they have created a really functional and practical design; the buttons are firm and feel well implemented no complaints here.
Now on to the screen what more could a person really want! It is clear, un-pixilated and just a pleasure to look at. If there is one criticism I have here it’s almost too shiny on a sunny day I can see this certainly picking up some glare, but really I am nit-picking now.
Unfortunately, as you will find with most if not all big touch screen DAPs and smartphones alike finger prints are just going to be smitten wanting to get a piece of that sexy sheen all over the front, and back so make sure you keep something to wipe her down if your anal about her remaining prestige. 
I am going to throw album art, videos and pictures in here just for the sake of it. After pushing in my Micro SD card all my videos, pictures and music were available instantly. As of yet there has been no problems with viewing any of the aforementioned. In fact all the pictures and videos were displayed incredibly clearly probably due to the stunning display. Album art for most songs were all there, I know there has been few issues with previous audiophile DAPs not displaying album art but there seems to be no problem here.
Output Location
In terms of the headphone out and line out location I’m not really sold on the idea of them being at the bottom of the unit. With the volume knob being located at the top naturally I would have assumed the headphone out would have also been located there for convenience but alas you can’t have everything you want.
Memory+ Expansion
Now there is something I have left to the last section as I really have had a slight issue with the SD card slot. Aesthetically this is probably one of the sleekest designs I’ve seen on portable music device. The problem lies when after I’ve slotted the memory card in it is just a pain to get out unless you have nails or something quite slim to poke down in there. This could have done with a touch more thought but I will say I love how the slide down cover masks the appearance of any additional bits or bobs. 
Battery Life
This is a nice step in the right direction on average I’m getting about 7-8ish Hours out of a full charge but bear in mind most of my listening is done via live streaming. I think with pre-loaded files held by the internal memory and with connectivity off you should be able to get the claimed 9 hours out of it. 
Charging time is really quite good give about 4 hours and your good to go that should last you about double the time if you’re a little conservative during use.
Sound quality
I am sure this is the main point why we’re all here so let me sum it up quickly it sounds really, really good. Oh the irony if I were to just leave it there no I’ll elaborate on this stunning piece as we go on I am going to break it down into file sections as I feel each hold their own level of quality.
All listening was done using the headphone out but I have added the little sub section below mentioning the quality of the line out.
Line out quality
Simply super-duper clean the line out adds nothing and takes away nothing. In comparison to say the Meridian Explorer’s line out you can hear the difference in an instant so synergy is a lot more important in this instance. I personally love the Meridian’s sound but it has a tendency to add its own personality to whatever amp you decide to partner with it.
I only have my trusty Vorzuge Pure ii amp for reference but what I hear is just what you’d expect to hear from such an honest milky amp. I have plugged my Pure ii into a few devices with some adverse effects not the case with the AR-M2 it’s exactly how it should be everything that holds true to the character of the Pure ii the sound is simply there without any mess or sudden schizophrenic changes.  
Online Streaming Using Spotify
This is my preferred method of listening because I didn’t feel to transfer my entire music library and it also means I have an almost limitless selection of music at my disposal.  First things first with good Wi-Fi connectivity there have been no problems I have encountered at all. Streaming has been smooth, quick and very responsive.
All the audio seems to have a beautiful composed tone that makes everything sound incredibly clean and effortless. I can sense a slight lift in the vocals when using most earphones and headphones. But I am warning as a vocal lover some tracks did display a slightly V shaped response.
One thing in particular I love about the way this device portrays the music is how clear and detailed the music is without ever sounding hard edged or sharp. Every detail is there from clicks to the subtle breaths of the singer as they inhale to exhale there next word.  Soundstage is very realistic it has great width, depth isn't the greatest but still very good however I don’t think many will pick up on this unless you are clinically listening.
It is worth mentioning the earphones I’m using do not hold the greatest depth of soundstage but the Meridian + Vorzuge set up I use holds the edge in this department. In comparison there is certainly a noticeable difference when switching from my iPhone 6 which is a touch more mid centric and has a much more 2D sounding soundstage.
Higher Bit Rate 24/192
Now whilst all of the above hold true for the following write up without repeating myself too much I’ll try and explain some of the most important differences when you are listening to up scaled music.
I wouldn't have thought many would really hear a night and day difference between the iPhone 6 running Spotify and the AR-M2 if I am completely honest. On the other hand when switching to some of my acoustic music, which I effortlessly uploaded from HD Tracks, there is a difference and yes it is clear.
The best way I can describe it would be to present you this image so use your imagination if you will. You’re driving in your Aston Martin Vantage 2dr 420 down a long, winding, smooth, sunny road and during your exhilarating journey you notice the subtle warmth of the sun as it kisses your face. Then you suddenly remember you can let that luxurious soft top down and experience this pleasure in its rawest form. The top slowly descends and as it does you feel the truth, that unexplainable embrace of fresh air and friendliness as all becomes clear. You’re enjoying the journey the way it should be no restraints just pure unadulterated love flowing as you wind and dance with the road and your surroundings.
Ok well I may have embellished on that a touch but on a realistic scale if you are considering buying this player I would do so being prepared to have everything ready to feed it. The differences between a compressed file, streaming and uncompressed are night and day to a discerning ear.
You will find stringed instruments suddenly have more room to breathe, there seems to be almost boundless space that surrounds you and it’s like you finally stop getting this persistent urge to analysis the music so you can finally relax.
DSD Files
I haven't had the privilege of trying out any DSD or DXD files so I am borrowing a quote from [b][color=red]AlanYWM[/color][/b] hope he doesn’t mind: “I tried DSD on my micro SD card but the machine seemed to be "stammering." It worked fine with 16/44 files. The surprising thing was it played DXD files from its internal memory without any hiccups. So I am wondering if the micro SD card had anything to do with the "problem" I encountered.
Issues and Improvements
So far there has been static sounds when the music is stopped but this mainly seems to occur when connected to Wi-Fi. I have spoken to Robert and he thinks this may be a problem to do with some of the pre-production units so I will keep this section updated as and when changes are made. (After some headphone and earphone switching the problem seems to mainly occur with BA type earphones exclusively. So this is a brief heads up to those looking to partner this with anything BA related sorry guys.)
Update ok after the new unit had arrived I experienced no issues with interference or static. This unfortunately didn't last forever since downloading Spotify the same problem has redeveloped I have uploaded some footnotes below emailed to me by Robert to help everyone get a better understanding of what is happening. 
Screen Animation and Wi-Fi noise


The key for the better sound from the M2 is a full two-stage analogue amplifier.  The headphone amplifier works exactly like a power amplifier and it amplifies everything at full power. 


You hear noise because:

- The screen generates noise

- Wi-fi can generate noise

- Without interference, the noise floor is incredibly low

- The amplifier is about 30 to 40 times more powerful than the competition and everything including noise is amplified

- With both screen and WiFi off, no noise should exist



- With large headphones there is no problem.

- With extremely sensitive low impedance IEM, you may hear some noise in silent parts of the music.  

- The noise from activity of LCD touch screen (e.g. full screen animated changes) and Wi-Fi will become audible.  


If we make the unit as feeble as the competition, we can avoid the noise.  It’s essentially a side effect of the HIGH-POWER AMPS



Some noise arises from the use of the LCD Screen and from screen animation

As the screen switches off automatically when idling, this should be no problem when listening



Using extremely sensitive low impedance IEM and with Wi-Fi on, you can hear noise if the volume is set high without music playing

However playback music at any sensible volume and you will deliver excellent sound quality and sufficiently dark silence.



This is the price for great sound. Again, the key is the full two-stage analogue amplifier (pre-amp and power-amp).  The whole analogue circuit consumes constant high power regardless of output level.  Even if there is no sound, the analogue circuit is consuming the same power as full output.  To keep the high sound quality and deliver a reasonable standby time, we need to shut down the entire analogue circuit when there is no music playback and switch it on only when there is music playback.  Switching the analogue circuit on and off produces a pop/click. This does not affect music playback.



The M2 uses two Crustal Clocks support accurate playback of two groups of sample rates:

ONE - 44.1/88.2/176.4/352.8kHz, DSD64/128

TWO - 48/96/192/384kHz


A click noise occurs when the system switches between these two groups.  

There should is no click noise if the two tracks have sample rate within the same group.


You do not hear such noise on classical Android or iOS devices because they actually stick to one specific sample rate (e.g. 44.1kHz only) and convert everything to that specific sample rate by software.  Such product do not really have a real sample rate change in hardware.

Yes the pops and static are a little annoying but certainly not a deal breaker.
Personally after spending more and more time with this player I am becoming too smitten to go back to any other of my sources. This however will not by any means be an end game product for some. So what is lacking? Well there are so many variables but if we really pick this deal apart in comparison to some of its competitors Fiio’s own X5 doubles as a DAC point Fiio, price is a little steep with new high end DAPs coming out left right and centre Cayin N6, even though I almost feel like saying the AR-M2 is a bargain there are other options out there for a more budget concerned person, then of course outputs no balanced mode for those dedicated to true audiophile nature no optical out etc.
But this is where I am putting my foot down. As it stands this is hands down the best piece of equipment I have tried sound is subjective yes but this is a machine built for its purpose and is worthy of the title in my opinion “A True Audiophile DAP”.  In its nature that is exactly what it is a modern day android based Audiophile player no bells and whistles but damn who needs them when you’re enjoying your music this much.  
-          Solid build quality
-          Stunning sound
-          Great UI simple and effective
-          Good battery life
-          Lacklustre Accessories
-          Nice design (Matter of opinion)
-          Incredible driving capability  
Unfortunately guys there are going to be a few things I won’t be able to shed light on during this review simply because I do not have access to certain pieces of equipment at the moment. If at any point any Head Fiers would like to have some comparisons to other high end Daps they own and would care to lend a hand I’d be more than happy to take the time to write up some comparative notes.
Thanks for reading as always if there are any questions please feel free to ask. I will do my best to update the review as and when necessary. 
Well its been a long journey and thanks to this review ive found audio nirvana. Growing up with top end hifi has been a privilege and a joy. After many years out of the audiophile scene, i decided to try the idea of using my phone as a transport and a separate amp/dac. My first foray into the unknown was with the fiio e18 Kunlun. It sounded great compared to my phones wolfson dac and lifted the veil of muddiness offf my recordings. I knew i could better this and the hunt was on for a better dac and amp. Enter the Sony PH2 again it moved the bar another notch and whilst the e18 matched it on clarity it could not create the soundstage that was presented in front of me via the PH2. Ok some would say stop there and enjoy what you have got but pandoras box was sitting there saying OPEN ME. I had read this guys review and just had to dip my toe into the water to see what all the fuss was about.
After parting with a large amount of well earned money i bought the Acoustic Research M2. This was about to change my perception about DAPS full stop. Before i listened to my purchase i borrowed a Astell and Kern AK240 to give me a taste of audiophile royalty. Ok here we go. 
Make no mistake, the ak240 is fantastic and delivers the goods in aplomb but the M2 is so much better in many ways. The soundstage of the M2 is so special and when used with either LCD-2 or HD800/700, it raises the bar by creating not just a space but a chasm that you could close your eyes and physically see the universe that is set out before you. Another plus point of the M2 is the point of focus of instruments or vocals placed in your universe. Again close your eyes and the instruments and vocals are placed out in there own space with such precision to shame a architect. Im not saying that the ak240 is bad but i couldn't recreate the emotion that i felt with the M2. Very few HiFi components have stirred such emotion in me. The last item that had this effect on me was my Sonus Faber Stradivari Homage with a McIntosh C2500 combo and a musical fidelity Nuvista cd player. That bit of kit got me back into hifi and i owned it all until 5 years ago when i moved house and decided to down size. Since then ive been trying to find a portable solution to my lavish tastes and now ive found it. If i had not read the above review from dnun8086 i would have been still been wasting money on different solutions and getting nowhere. A word of warning though. Dont expect to play games or facebook or whats app on this machine, yes its android but its scaled down to do one thing and do it well and that its to produce music to such a high degree of accuracy and detail. Dont skimp on your headphones either, the analogy i use is if you had a Bugatti Veyron, you wouldn't use budget tyres on it. This unit deserves to be listened to and please compare and you will be astounded. Its a audiophile dap full stop.
Astell and kern need to give Acoustic Research the keys to the castle ,its time is over. The king is dead...
Wow thanks for your comment and I was glad I could help out with you making a decision and open you up to a whole new world of audio again. I love this community because that is what we are about at the heart of it, great sound and that's just what I feel the M2 offers up. Thanks again for commenting! 
Hi, dnun8086 -
I notice you've sold your M2; have you found a better DAP? What are your thoughts on the Questyle QP1R?