Acoustic Research AR-M2 hi-rez portable player Page 2

However, I had some problems with Apple Lossless files. The 24/96 ALAC files of Beck's Morning Phase (Capitol/HDtracks) played okay, as did the 24/88.2 ALAC files of Random Access Memories. But some ALAC files at 88.2 and 96kHz were incorrectly identified as "44.1kHz" and played at half speed. This was true with my own recordings and with some commercial recordings, such as Richard Egarr and the Academy of Ancient Music's of J.S. Bach's Brandenburg Concertos (Harmonia Mundi), and Sara K.'s Play on Words (Chesky). With some 192kHz ALAC files, the sample rate was again identified as "44.1kHz," but these files wouldn't play at all.

These rogue files played correctly on the Pono, Questyle, and Astell&Kern players, on Aurender and Antipodes media servers, and on my Mac mini running Pure Music and Audirvana. On investigating this problem, however, I realized that every one of the problem files had been transcoded from an AIFF original with iTunes. I Dropboxed examples of some of these files to AR's Arex Li, who responded that "the file headers were misread and the files were misrecognized as 44.1kHz files. While M2 switches the clock according to the file for native playback, a wrong clock was used to play the file. My software engineers have already identified the issue and prepared a fix. We will verify the fix and send it to you."

I installed the revised version of the AR-M2 firmware (v.2.5.1) when I received it. All the rogue files now played correctly, and the new version of the app also added gapless playback, which I verified with some symphonic files where there was no pause between movements. It was time for some comparisons.

Against the Astell&Kern AK100
I compared the AK100 with the AR-M2 with levels matched by ear, and listened through the AudioQuest NightHawks. "Heart Like a Drum," from Beck's Morning Phase (24/96 ALAC, Capitol/HDtracks), sounded cleaner on the AR, with less "fog" at low frequencies. This was the opposite of what I'd expected, as the AK100's output impedance is twice that of the AR. Recorded detail—eg, the piano vamping under the guitars in the verses—could be heard a bit more clearly than on the AK100. Advantage, the AR-M2.

Against the PonoPlayer
Playing Rachmaninoff's Symphony 2, with Iván Fischer conducting the Budapest Festival Orchestra (DSD64, Channel Classics 21604), the Pono didn't quite match the dynamic swings of the AR-M2. When I drove the Audeze 'phones single-ended and again matched levels by ear, the Pono sounded quieter than the AR: the orchestral flare-up with the Tchaikovsky-esque brass choir some 11:00 into the first movement was not as overwhelming. The ambience surrounding the orchestra seemed better resolved with the M2, as was the space around the solo clarinet in the second movement. However, it was a close call with these two players: The Pono was sweeter with that glorious melody in the symphony's slow third movement, the AR-M2 airier; the Pono was a little more involving, the M2 a little more resolving.

Against the Astell&Kern AK240
When Michael Lavorgna reviewed the AK240 in November 2014, he wrote: "While I've heard more lush, ripe presentations . . . [u]pper frequencies were finely detailed, yet never edgy or too sharp. Its combined strengths of superb resolution and clean, clear, fatigue-free reproduction made it a joy to listen to." I spent a weekend with the AK240 using LCD-X and Ultimate Ears 18 Pro IEM headphones, and my own feelings about this expensive player echo ML's.

But returning to the AR-M2, I didn't feel I was taking much of a step down in sound quality. With the forceful quality of the double-bass groove in "Ode to Billy Joe," from Patricia Barber's Café Blue (DSD64, Premonition/Acoustic Sounds), and the gloriously real-sounding quality of the reverberation behind Barber's voice and finger snaps, the two players sounded very close to one another, and equal in their powers of resolution. Perhaps the AR-M2 slightly emphasized the sibilance, and perhaps the double bass sounded a bit rounder through the AK240—but, again, the differences were small, and may well have been due to the inevitable difficulty in matching playback levels by ear.

On balance, if I didn't have to count pennies, I'd go for the $2500 Astell&Kern—but for $1300 less, the Acoustic Research comes very close.

Streaming with Tidal
With WiFi capability and preloaded with Tidal and Spotify apps, the AR-M2 comes ready for a streaming world. Linking the Tidal app to my account took less time than it did for me to write this sentence. What, then, to play? Glenn Frey's death in January prompted me to listen not to "Hotel California," "One of These Nights," or "Take It Easy," but to "New Kid in Town," from the 16/44.1 remastering of the Eagles' Hotel California (Elektra/Asylum). This is a beautifully engineered recording, and the AR-M2 got everything right: the gentle pathos in Frey's lead vocal, the vocal harmonies that soar upward to emphasize the key change after the solo bridge, the chiming quality of the chords with which Don Felder begins his guitar solo, the softened low frequencies of Randy Meisner's guitarrón, the restrained tastefulness of Joe Walsh's interjections on electric piano. That experience triggered an afternoon's worth of enjoyment streamed from Tidal. I suspect that the ability to stream true CD-quality audio from Tidal will be the selling point for many buyers of the AR-M2.

Each of the four personal players I used in preparing this review offers a different combination of features: the PonoPlayer plays only audio files; the AK100 has digital input and output and can be used as a DAC; the feature-rich AK240 also adds WiFi capability and native DSD playback; the AR-M2 dispenses with a digital input but is almost as versatile as the AK240 at less than half its price. And when it comes to sound quality, I'd be hard put to choose between the AR-M2 and the AK240.

I recommend the AR-M2. It's good to see the Acoustic Research brand applied to such a well-engineered product after all these years. It's just a shame that the beautiful-looking and -sounding AR-M2 couldn't be made in the US—let alone in Houghton Regis!

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.