Acoustic Research AR-M2 hi-rez portable player

In the early 1970s, I lived in a village 40 miles north of London, England, and regularly drove through an only slightly larger village called Houghton Regis. And every time I did so, this budding audiophile was thrilled to see a factory in the High Street with a nameplate proudly announcing that it was the site of Teledyne Acoustic Research's European operations. I was aware of the American brand because of a chance encounter with a pair of Acoustic Research LST speakers, and the geographical connection led to an increased interest in their speakers (footnote 1). A sort of local-boy-, er, local-multinational conglomerate-makes-good story. Sort of.

By 1967, AR was owned by Teledyne; Acoustic Research had been incorporated by Edgar Villchur in 1954 to manufacture his ground-breaking acoustic-suspension loudspeaker designs, and by the beginning of the 1960s had become a major speaker brand. Teledyne sold AR to International Jensen around 1985, and in 1996, Jensen, including AR, was sold to the Recoton Audio Corporation. In 2003, Recoton in turn sold AR to Audiovox (now Voxx International). With each change in ownership, the company's legacy of audio engineering seemed further diluted, and by 2015 I was aware of the AR brand only as a logo seen on products aimed at the mass audio market, such as Bluetooth speakers and accessories.

Then, out of the blue, I received a press release about an Acoustic Research hi-rez audio player, the AR-M2, scheduled to be launched in the US at the end of 2015. Priced at $1199, the M2 was clearly aimed at audiophiles. Wiping away a tear of nostalgia, I asked for a sample to review.

The "AR High-Resolution Reboot"
In 2011, the Voxx Corporation began what they called the "AR High-Resolution Reboot" project, based in Hong Kong. The first products were limited to the Far East, but the brand has now reached the US, and the Acoustic Research AR-M2 is the first product to appear here. In its press release, Voxx stated that "The new Acoustic Research High-Fidelity division is a very serious company . . . very well funded for R&D, manufacturing and global distribution. The designer Arex Li and his colleagues are purist audiophiles and music enthusiasts and they are bringing some great products to market. The brand is committed to long-term support of all their products and will gradually expand the range."

The AR-M2
The AR-M2 is almost the same size as an iPhone 6S, but thicker. Like the iPhone's, its front panel is a 5" glass touchscreen, and on the right of the aluminum frame are four buttons—On/Off/Wake, Play/Pause, and Song Forward and Back—plus a sliding door that conceals a slot for a microSD card of up to 128GB capacity. (The M2 comes with 64GB of internal storage.) Along its bottom edge are 3.5mm jacks for Line and Headphone outputs, plus a mini-USB port for charging and for connecting the M2 to a host computer. A single full charge of the 4200mAH battery is claimed to last nine hours, which was pretty much my experience. Inset in the top right of the case is a knurled volume control with a premium Alps potentiometer. The review sample came with a leatherette flip case; the overall effect of the industrial design is of a piece of premium gear.

The AR-M2 runs the Android operating system (v.4.3 in the review sample), and once it's booted up, it's unlocked just like a smartphone: by swiping an icon to the side. Files are played with the AR-M2 Music Player app (v.1.06 initially installed), but tapping the Menu icon brings up an array of Android apps and widgets, also just like a 'phone's. Not only are the usual Clock, Calendar, Calculator, and Web browser available, but so are apps for Tidal and Spotify streaming—yes, the M2 offers WiFi connectivity.

Under the hood are two temperature-controlled master crystals; the main processor is a quad-core Qualcomm Snapdragon. The Android OS is bypassed for playing high-resolution files with AR's Music Player app, which offers a graphic equalizer, bass boost, and something called "3D Effect." (I left these bypassed for my listening.) The DAC chip is a premium, 24-bit Burr-Brown PCM1794A, which accepts sample rates up to 192Hz. (The datasheet for this chip doesn't list DSD compatibility, so it's possible that the M2 transcodes DSD to hi-rez PCM before decoding the data.) The player's output stage is claimed to be biased into class-A; the M2 did get warm after an hour or so of use.

Context and Listening
We have reviewed several portable hi-rez players: the Astell&Kern AK100 ($699), in August 2013; the Astell&Kern AK240 ($2500), in November 2014; the PonoPlayer ($399), in April 2015; and, most recently, the Questyle QP-1R ($899), in December 2015. Following our reviews of the Astell&Kern AK100 and the PonoPlayer, I purchased the review samples to use as references. I also had on hand our review sample of the A&K AK240.

I copied files to the AR-M2's internal storage via USB, using the Android File Transfer app for Mac, and installed a 64GB microSD card loaded with my favorite music. I did most of my listening with Audeze LCD-X headphones. With the AudioQuest NightHawk headphones, the sound was rich—perhaps a little too rich. The better-defined bass of the Audezes was a more optimal match with the AR-M2's weighty low frequencies. The 16' register of Nathan East's bass guitar in "Get Lucky," from Daft Punk's Random Access Memories (24/88.2 ALAC file, Columbia/HDtracks), sounded solidly Stygian through the LCD-Xes, slightly too loose with the AudioQuests.

The rich, extended low frequencies were matched at the other end of the audioband by airy-sounding highs. The brushed snare and closed hi-hat cymbals in "Anyone Who Had a Heart," from Shelby Lynne's Just a Little Lovin' (DSD64, Lost Highway/Acoustic Sounds), were delicately palpable. And Lynne's voice—delicious, just delicious.

AT the time of the review, Acoustic Research didn't include lossily-compressed MP3 or AAC files in the list of formats the AR-M2 will play. This was due to a website error that has since been fixed, with MP3 and AAC now included, and the AR-M2 did play a 256kbps AAC file of Nat King Cole singing "Nature Boy" (Capitol), which I'd bought from iTunes, as well as a 256kbps MP3 file of "Bullet with Butterfly Wings," from Smashing Pumpkins' (Rotten Apples) Greatest Hits (Virgin), purchased from Amazon. Also, AR lists DXD files under the formats supported, which are sampled at 352.8kHz. I don't have any DXD files, but playing a WAV file of a 1kHz tone sampled at 384kHz resulted in pink noise.

The AR-M2 played every DSD64 and DSD128 file I tried, including Lyn Stanley's Potions: From the 50's (A.T. Music/Acoustic Sounds). Stanley's sultry voice sounded uncolored and forceful, and the double bass was rich. FLAC, AIFF, and WAV files with sample rates up to 192kHz played without any problems, and the AR-M2 sounded glorious. I was present for one of the sessions for Three's Company's We'll Be Together Again (24/192 AIFF, Chesky)—playing "Dark Eyes" from this binaurally recorded album, the AR-M2's reproduction of the space around Ron Carter's double bass, Javon Jackson's tenor sax, and Billy Drummond's drums transported me back to the dusty, deconsecrated church in Williamsburg, Brooklyn, in which this music was recorded.

Footnote 1: A decade later, when I was the editor of the UK's Hi-Fi News & Record Review magazine, we used the Houghton Regis facility's anechoic chamber to test speakers.
Acoustic Research
3502 Woodview Trace
Indianapolis, IN 46268
(844) 353-1307

spacehound's picture

I wonder if it can drive a typical 'line' input to reasonable levels? My iPad can't. Nor will its 'Lightning' output at a high enough level into a USB port. You can't really tell from the specs.

So for the future it might be helpful if you could try this and tell us. (I was too tight-fisted to order the optional Burmester audio in my car so now need an external player.)

AR? I've still got, and use, their turntable, later copied by Linn. Bought it from the local branch of Laskys. Do you remember them too?

John Atkinson's picture
spacehound wrote:
I wonder if it can drive a typical 'line' input to reasonable levels? My iPad can't.

It will have no problems driving a line input, especially from the headphone output.

spacehound wrote:
AR? I've still got, and use, their turntable, later copied by Linn.

That's unfair. Yes, both were belt-drive, suspended-subchassis turntables, but that's where the comparison ends. The original AR was still a good turntable but was let down by a poor tonearm.

John Atkinson
Editor, Stereophile

spacehound's picture

Castle Engineering was a small machine shop and copied the Ariston turntable design that they were contracted to make some parts for, right down to the lid, then sold it as their own, changing their name to Linn at the same time. That's how Linn got started in the audio business. There was a court case about it but it never came to anything for or against the two opponents.

Thanks for the AR output data. I tried it and it's fine. But only a demo model, the dealer hasn't got any stock at the moment.

jhanken's picture

In terms of function this is approaching perfect, with PCM, DSD and Tidal, but the omission of MP3 and AAC to me is a bit heartbreaking, I still have some music in those formats that I cannot get otherwise. I am really hoping to have just one portable player for everything. In the review, you said one AAC file actually played fine, any chance you could please test a 320KB MP3 and verify that it would play properly? Thanks, and very grateful for this review!

John Atkinson's picture
jhanken wrote:
In the review, you said one AAC file actually played fine, any chance you could please test a 320KB MP3 and verify that it would play properly?

The AR-M2 player has long since been returned to the manufacturer, but I did play 256kbps MP3s with it without any problems.

John Atkinson
Editor, Stereophile

robfol's picture


The M2 plays almost every format under the sun, including MP3 of all shapes and sizes and AAC, plus FLAC, ALAC, WAV, AIFF, APE DSD64/DSD128 & DXD. Sensible future formats will be addressed by our regular firmware updates.

Unfortunately an error on our website led JA to believe that these base formats might not be supported.

Regards Rob Follis for Acoustic Research

Long-time listener's picture

I spent about an hour listening to the M2 at a local dealer, with my own headphones and music. Aside from generally good clarity and lack of obvious grain or sibilance, its most appealing aspect was its spacious soundstage, which is hard to give up once you've gotten used to it. But at the same time, the soundstage seemed sort of artificially "inflated," and its excellent bass likewise seemed a little boomy or artificially inflated, and the sound was slightly "dry." (And the Alps potentiometer was making noise as it turned.) The guy in the store also told me that downloads of gapless capability aren't available yet for the general consumer, even if they are for John Atkinson--and gapless is a VERY fundamental feature that should be standard on every player.

The Fiio x7 doesn't have that wide open soundstage, but it has a slightly more liquid, full-bodied, and rich character, with equally good clarity and freedom from glare or sibilance. Bass is equally good, and more natural. It also comes gapless out of the box. At about two-thirds the price, I have to consider the Fiio X7 an equally good player and a better value. Combined with the clarity, balance, and full-range response of my single dynamic driver NuForce NE-800M, it sounds marvelous.

robfol's picture


The 2.5.5 firmware with gapless capability and a lot of other tweaks and upgrades will be available within the next 10 days

Regards Rob Follis for Acoustic Research

Long-time listener's picture

And all else being equal, it has to be said that the player with the better soundstage certainly brings the listener one step closer to true realism in sound. And the M2 certainly has the soundstage, so it must be doing something right... If I had known about the M2 sooner, I believe it would be my player now instead of the Fiio.

dce22's picture

Chord Electronics Mojo DAC + Samsung Galaxy S7
4.8 Volt 0.7 Ohm Output Impedance
(Will work perfectly with all the headphones on the market)

Acoustic Research AR-M2
3.7 Volt 10 Ohm Output Impedance
(Will work properly with 100 Ohm or more Headphone Impedance)

Chord Mojo has 10db less distortion and 10 db less noise at all frequencies has better oversampling filter will work with every headphone there is, can be a DAC for your home system and for the same amount of money you can buy top of the line smartphone and Mojo DA instead AR-M2

PS. I am no way affiliated with Chord Electronics or Acoustic Research I am just parroting reality.

robfol's picture

Well, if you are a fan of expensive rubber bands, dangling cables and pocket destroying lumps? then that would be a great solution. In the meantime the M2 is an amazing performer at half the price of relevant competition. Cheers, Robert for Acoustic Research

TheNoose's picture

I wish all reviews would identify if the unit will output balanced audio and to what extent/format. Esp at this level of player. For example the Pono provides this functionality at 1/4 of the price here...and yet this was not tested or used as a benchmark. I wish it was.

robfol's picture


Balanced out adds complexity and cost for in our opinion, little benefit on a portable device. The M2 does not have balanced output.

Regard Robert Follis for Acoustic Research

TheNoose's picture

Acoustic Research is such a renowned brand. I wish there is an opening for me/customers in your statement Robert. It feels like talking to Apple, we know what you need best and aren't listening to you anyway. I wish it wasn't so.
On the ummmm...upside...why don't you buy a couple of balanced out portables say from Astell and Kern and Pono for example and using proper balanced cables and headphones give them a try? I'm sure like me and thousands of other customers and experts you'll hear a difference worth investing in. You could really redefine this facility with the power of your brand...Sincerely.

The Federalist's picture

I was very interested in the AR product when I first stumbled across it on Head-fi, and came very close to dropping $800 on the 2nd gen AK100 but the sheer number of units (from dozens of different manufacturers) up for sale on Head-fi classifieds, on a given day, leads me to believe the product type, while attractive, doesn't have much staying power with people once the whole consumer cycle has been completed and the drugs have worn off.

I would love to see something along these lines that was a larger screen, like an audiophile tablet so to speak, but with the same mechanical transport controls like these smaller units have.

So far the closest I have seen is the Nativ player on Indiegogo but that one is tethered to the wall via mains power so is a different animal.

I do think a lot of people have an aversion to using their phone or their tablet for music delivery. It's pretty clear considering how robust this segment is. I just think a bigger screen would draw you in a bit more. The phone form factor doesn't do it for me.

Either way. A very interesting device and a very good review. I do appreciate your take on this.


The Fed

Boogie6301's picture


Thanks for the review. I'm considering the AR-M2 primarily because of Tidal support. I currently have the QP1R and I'm more than satisfied with its sonic abilities albeit with crappy UI, no streaming and doggy scroll wheel.

Since your review of the AR-M2 came after the QP1R I'm interested to know your comparisons purely from sound qualities. Bluetooth, WiFi and streaming are "nice to have" for me so I'm not willing to compromise sonic qualities with these features.