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Acoustic Research AR-M20 DAP

  1. crabdog
    Acoustic Research M20 - Audiophile Grade High Resolution Audio Player - Poetry in motion
    Written by crabdog
    Published Apr 5, 2017
    Pros - Great battery life. Very large, high resolution screen. Exceptional sound quality. Powerful headphone output
    Cons - No physical playback buttons
    This sample was sent to me for the purpose of an honest review. All opinions and observations here are my own based on my experience with the product. I have no affiliation with the company and do not benefit financially from this review. More of my reviews can be seen from the link in my Head-Fi profile or on my blog.

    The AR-M20 can be purchased directly from the AR website:

    Acoustic Research Website

    The unit I tested came from Discovery HIFI in Bangkok, Thailand.



    I've owned several DAPs in the past and still have many more than I need. Most of them would be considered budget offerings as I get a kick out of ordering cheap players online and seeing what they have to offer. I had never owned any Android based players but was always curious to see what they were like as I always thought that playing music on my smartphone was a more pleasant experience, at least when it came to the GUI. Obviously the sound from most phones isn't comparable to a dedicated DAP although they continue to improve but still I prefer a dedicated DAP that doesn't take a toll on my phone battery and at the same time leaves my phone free for doing other things like email, web browsing and chat. Enter Acoustic Research and their Second Generation Acoustic Research M-Class Hi-Res Audio Platform which is based on Android but with a twist. What makes this DAP interesting is

    Utilizing a Burr-Brown PCM5242 DAC,  with a S/N ratio of 114dB and Texas Instruments TPA6120A2 among other things the AR-M20 is built around some impressive hardware and my expectations of its performance were quite high indeed.  So does the performance match the player's impressive specifications? Read on to find out.

    About Acoustic Research

    Acoustic Research was founded in 1952 and has a long history of innovation in Hi-Fi speakers. In 1983 it was acquired by VOXX International Corporation, a Global manufacturer and distributor of lifestyle products. Since 2011 the company has had a "Renewed focus on High-End and Digital". In 2015 they released their second generation M class Hi-Res audio player and USB-DAC. 2016 saw the introduction of the M20 as the third generation Hi-Res player. The company says they have "A long term commitment to excellence" and wish to "continue to honor the vision of the founder and to build sound systems that most truthfully reproduce the information they receive from recordings".

    Packaging and accessories

    The AR-M20 comes in a black box with white text. On the front is the Acoustic Research logo along with some of the player's features and a stealthy preview of the player inside. On the back are some more features and basic specifications. Removing the outer cardboard sheath you're presented with a simple but elegant textured black box with just the AR logo on the front. Remove the lid and BAM - there's the DAP in all it's glory but more on that later. Also included in the box is a quick start guide, a USB data/charging cable and a black felt carry pouch. The USB cable is thicker and looks to be of higher quality than the average ones you get with cheaper DAPs though whether this makes a difference in use is questionable since it's only used for charging and file transfers.

    20170310_220408.jpg    20170310_220425.jpg

    There was (in my opinion) one glaring omission in the bundled accessories and that is some kind of protective case. AR could learn a thing or two from other manufacturers in that aspect. Most DAPs, particularly high-end ones will provide a case in the box. Even just a flimsy silicone shroud would do the job of basic protection of the player and then the end user could have a choice of buying something more substantial or attractive later on. Due to the M20's high-gloss plastic rear by the time I'd inserted my micro-SD card the unit was already covered in unsightly fingerprints. On top of that I was afraid to put it down anywhere for fear of it getting scratched.


    At first glance the AR-M20 looks very similar to a high-end smartphone which is hardly surprising since the bulk of it is made up of the large 5 inch IPS screen. The screen has a native resolution of 720 x 1280 which produces vibrant colors and images. The all glass front has narrow bevels with the Acoustic Research logo at the bottom and is surrounded by a  silver colored CNC crafted metal chassis and certainly looks and feels like a premium offering. The back of the device is a high-gloss plastic that looks great but unfortunately it quickly gets covered in fingerprints and can easily be scratched so I'd recommend using a protective cover.

    On the bottom is the micro-USB port (supports USB-OTG), single 3.5 mm headphone out, LED charging indicator (red when charging, green when fully charged) and two hex screws. On the right side are three metal buttons - Power On/Off (or short press for screen on/off), volume up and volume down. The volume has 120  steps so gives you there's plenty of room for fine level adjustment. The buttons feel firm and have a nice tactile click to them though a little more resistance might have been nice to help prevent accidental presses. Under the buttons is the micro-SD card slot (supports up to 200GB) complete with a sliding cover to improve the DAPs appearance and prevent the card from being lost. The left and top sides are left bare but the top side has a raised bumper with two hex screws and the model number etched into it which is quite nice and is the single physical feature that distinguishes the M20 from a mulititude of similar looking smartphones.

    Dimensions of the player are 2.76 In (W) x 5.35 In (H) x .44 In (D)  and it weighs in at 177 grams. It's a good size which I find easy for single handed operation and sits well in your hand.



    The DAP is powered by a quad core Qualcom MSM8926 CPU and comes packed with 32GB of onboard storage.  As mentioned earlier there's a Burr-Brown PCM5242 performing the DAC duties and the TI TPA6120A2 headphone amplifier in class A/B configuration supplying up to 2.1Vrms output which is above average for a DAP in its class providing 16Ω: 228 + 228mW / 32Ω: 130 + 130mW / 300Ω: 15 + 15mW.  The M20 has variable native sample rate with dual crystal oscillators and supports all the modern digital file formats including DSD128 and DXD.
    Tying all this together on the software side is the Android 4.3 OS. Yes you read that right, 4.3. Now some people might think that belongs in the last decade but when you break it down it isn't really a bad thing. The M20 uses its own discrete audio path when running the AR Music Player, effectively bypassing the Android OS and avoiding any limitations or problems the software might introduce. So you get the benefits of the Android front end but avoid its audio limitations.

    The built-in wireless is 802.11B/G/N which has a maximum data rate of 11 Mbit/s so there is support for third party music streaming and apps such as Tidal, Qobuz and Spotify etc and the ability to download other apps. Apps cannot be downloaded via the Google Play Store but instead must be acquired from third party websites or via Amazon Underground. The reason there's no Google Play according to AR's technical director is:

    In my opinion this isn't a negative. After all if you're using Android apps you're not taking advantage of the M20's heavily customized OS to bypass the audio limitations inherent in the Android subsystem.

    User interface

    Anyone who has experience with an Android smartphone should immediately feel right at home with the M20 interface. When powering on the device the first thing you see is some text and model number at the top of the screen with the AR logo at the bottom. This is followed by an animation of the M20 with supported sample rates flying out from the center.


    Once the system has booted you'll see a familiar Androidish lock screen (screen lock can be disabled in the settings). Swipe the screen to unlock just like with any smartphone and the home screen will appear. In its out of the box state the home screen is fairly bare having only a clock, Apps/menu button, AR Player widget and the standard three Android navigation buttons (previous/back, home and running apps).

    In the apps menu the only things installed by default are:

    1. AR Music Player
    2. Browser
    3. Clock
    5. File Explorer
    6. Search
    7. Settings

    Navigating the UI is snappy and responsive thanks to the quad core processor. The M20's screen senses touch really well just like a modern phone whether browsing or typing with the on screen keyboard.

    shot_2017-04-02_08-49-17.png     shot_2017-03-27_19-40-11.png     shot_2017-03-27_19-39-45.png

    shot_2017-03-27_19-40-54.png     shot_2017-03-27_19-41-21.png     shot_2017-03-27_19-41-57.png
    shot_2017-04-02_08-44-22.png     shot_2017-03-27_19-46-01.png    ​
    AR Music Player
    The Acoustic Research custom music player lies at the heart and soul of the M20 and is the place from where you music is meant to be played. Along the top of the player screen are a number of tabs for music navigation and consist of (from left to right):

    1. All
    2. Albums
    3. Artists
    4. Genres
    5. Folders
    6. Playlist
    7. Now Playing

    In any of the lists you can tap and hold on an item to show the option menu from where you can select to play the item, add it to a playlist, show its details or delete it.

    Below the tabs is where the information or album art is displayed and takes up the majority of the player's screen. Album art looks great by the way in large vivid, colorful images. The one drawback about the now playing screen is that the song title, song information and bit-rate are superimposed over the top left corner of the album art which can be a little untidy and also hard to read if the album cover is a light color.

    Under the artwork are the player controls of which there are two rows. The first row contains (from left to right):

    1. Settings (Settings, Audio Mode, Sound effects)
    2. Favorite
    3. Shuffle Mode
    4. Repeat Mode

    and in the second row are Skip backward, Start/Pause and Skip forward. The sound effects screen has a number of preset EQ settings and a custom user EQ, along with Bass boost and 3D effect.

    Overall the AR player is well thought out and very easy to use. What's really great about its implementation is that there is no need to boot into a separate OS to bypass the Android audio path as it's totally integrated. The current firmware version (V1.3.6.0-BT) added gapless playback and I can confirm it works perfectly. I was also informed that there will be an update in the near future adding a music search feature and some other improvements to the AR Player.

    shot_2017-03-27_19-42-48.png    shot_2017-03-27_19-45-29.png     shot_2017-03-27_12-21-11.png

    shot_2017-04-02_08-44-47.png     shot_2017-04-02_08-45-08.png     shot_2017-03-27_19-43-38.png
    shot_2017-03-27_19-44-36.png     shot_2017-04-02_08-45-55.png     shot_2017-04-03_22-56-49.png

    For the sake of testing I installed the current version of Tidal ( from a third party website. Everything went smoothly and it works perfectly. Loading time is fast and streaming is flawless on my home WiFi. I downloaded several albums using the Offline Content function and the speeds were very good. Music on Tidal also sounds great despite going through the Android generic audio path but then after all it still utilizes the excellent Burr-Brown DAC.

    shot_2017-04-02_08-42-20.png     shot_2017-04-02_08-44-00.png


    I was able to easily connect via Bluetooth to my Samsung Galaxy Note 5, Brainwavz BLU-200 earphones, Wharfedale Diamond Active and Arcam irDAC-II. Because of the AR Music Players' discrete audio path music cannot be streamed from it but there was no problem playing all my tracks from Tidal, third party music applications like Poweramp or other streaming services like Spotify etc.


    Some readers might find this section a little on the "lite" side after seeing other reviews that wax lyrical about how their DAPs sound with various headphones and IEMs but in my personal opinion that essentially breaks down into a series of mini reviews of those headphones and IEMs... A DAP will have a basic signature (hopefully close to flat) that carries across to whatever you connect to it so while I will cover some pairings below, this section will be a very brief description of how I hear the M20.

    Presentation is full-bodied and powerful, smooth and resolving but still remains linear and carries across all the details present in the recording. The dual crystal oscillators with their variable native sample rate tackle any kind of format with apparent ease, rhythmic precision and timing with everything from progressive psytrance to jazz instrumentals and hard rock.

    As you can see in the image below the response across the frequency range is flat except for a slight dip at 4k and 6k under load. Whether this is intentional or not I can't say but to my ears there are no details lost as a result.

    Loaded test using the triple hybrid (1DD + 2BA) Moni One IEM which has an impedance of 16 ohms.

    Pairing (full-sized)

    Ultrasone Performance 860 32 ohms

    The 680 has a linear signature and it is very resolving for a headphone in its price bracket and with the M20 I was hearing details that I hadn't noticed before on some old tracks that I'm very familiar with. The full-bodied presentation of the M20 really makes this an outstanding match up.

    Beyerdynamic DT990 Pro 250 ohm:

    The swirling sub-bass in "Lost Whispers (Intro)" by Evanescence is driven along surprisingly well by the M20 and doesn't sound lacking in any other areas either. The specified output power is 16Ω: 228 + 228mW / 32Ω: 130 + 130mW / 300Ω: 15 + 15mW and for my listening I hover around 75-90% volume with the DT990 depending on the recording and my mood. So I'd say the M20 can comfortably push 250 ohm headphones but 300 ohm (HD600) and over might be asking a bit much without additional amplification.

    MSUR N650 32 ohm:

    MSUR's N650 is a warm sounding headphone so I wasn't sure how this pairing would go. It actually surprised me because it seemed to really lift the treble and bring them to life. Listening to "Jazz at the Pawn Shop" by the Arne Domnerus Group is a real treat with this combination as they seem to have a real synergy going on with oodles of detail and realism.

    From left to right - MSUR N650, Ultrasone Performance 860, Beyerdynamic DT990



    Pairing (IEMs)

    I'm not going to cover these individually but will just state that with all  of the IEMs I've tested with the M20 there was no evident background noise or hiss. It carried over the same characteristics as it did with the full-sized headphones - rich, resolving and full-bodied, like a glass of fine red wine.

    IEMs used for testing:

    1. LZ A4
    2. TFZ Balance 2M
    3. Campfire Audio Andromeda
    4. Campfire Audio Vega
    5. Thinksound ms02
    6. Moni One
    7. Trinity Audio Phantom Master 4



    Battery life is listed as 16 hours and I found that to be fairly accurate, though that is 16 hours of actual playback time. I found that if listening to music for 3-4 hours per day the M20 can easily last for several days on a single charge. Turning off WiFi when you're not streaming can eke out even more time. One of the benefits of the M20 is that there's never really a need to actually turn off the device, you can just stop playback and let it sit as you would with a smartphone. When you want to use it again a short press of the power button brings it to life immediately. That's due in part to having a heavily customized Android OS running things because once a lot of those extra features and apps are removed it becomes a very energy efficient platform.


    Regretfully I don't have any other Android based DAPs or anything else in this price range so it seems nugatory to make a comparison with my other gear at this stage. Perhaps this section will be updated at a later date.

    Some extra things I would have liked (these aren't cons as such but just things that could make the experience even better and of course it's completely subjective):

    1. Primarily a protective case, even the most basic silicone blob would suffice and at this kind of price point it's pretty much expected when buying something of this caliber.
    2. An independant line out function for connecting to external devices (the headphone out can be used in most cases but imo isn't ideal)
    3. Physical playback buttons so you don't need to turn the screen on to skip/rewind etc.


    There are several reasons that non-audiophile or casual listeners are content with using a smartphone for playing their music. With large, high resolution screens, powerful processors, vibrant album art and "pretty good" sound it's all they need.  I've long wished for a source with a similar GUI experience as I get on my phone for browsing and playing music added with the uncompromising audio quality of a dedicated DAP and that's exactly what the AR-M20 delivers with its Android interface and Burr-Brown DAC.

    Additionally you can connect via wireless to Bluetooth devices such as external amplifiers or headphones, browse the internet and run streaming applications. Oh and did I mention this thing is gorgeous? The M20 is a great portable device with powerful, transparent and linear presentation and the resulting sound that comes from it is nothing short of exceptional.


    1. View previous replies...
    2. crabdog
      @Matrix Petka the processor seems fine to me. No lag in interface whatsoever, apps load fast. I don't know if you expect to play Mario Kart on it? The M20 is $699, you're talking about the M2. Yes, it's a shame about no balanced out but the new M200 has that and it's cheaper too.
      crabdog, Apr 10, 2017
    3. Matrix Petka
      Sawasdee ka, crabdog :)
      Sorry, you are right - price 699, sorry. Anyway for this price you can go for Onkyo DPX1 with balanced and much better hardware. Recently curiosity led me to buy FiiO X5 3 - it have some issues, which, I think, are caused by processor - lag and clipping on HR files, especially on 24/192.
      Matrix Petka, Apr 10, 2017
    4. crabdog
      @Matrix Petka Sawasdee ^_^  I'm a bit disappointed with FiiO after my experience with the X1ii. Still I hope to get a chance to try the X5 3 at some time but yeah I think there might be better options. Would love to try the Onkyo myself too!
      crabdog, Apr 10, 2017