Acoustic Research M2 review

Super-powerful, seriously pricey and sonically sublime.

Acoustic Research M2
Super-powerful, seriously pricey and sonically sublime.

TechRadar Verdict

It terms of sound quality the M2 is a superb device, able to deliver a wide range of file formats in exquisite detail. There are a few issues, but these are more to do with general usage, so if you prioritise sound above all else you may be able to forgive the M2 its trespasses.


  • +

    Fantastic sound quality

  • +

    Good storage

  • +

    Seriously loud


  • -

    Slightly weak battery life

  • -

    Awkward OS restrictions

  • -

    Chunky and weighty

Why you can trust TechRadar We spend hours testing every product or service we review, so you can be sure you’re buying the best. Find out more about how we test.

Acoustic Research may not be a household name, but its M2 portable audio player is an incredible-sounding device, and a mighty powerful one too.

Similar to the Pioneer XDP-100R we checked out recently, the M2 is also rocking a version of the Android operating system to give it familiar, and versatile, control software. But the M2 is filled with audio components that are even more high-end than Pioneer's player, and generates what would be ear-splitting levels of volume were the audio quality not absolutely stunning.

But everyone's phones have the capacity to store, stream and play music now, right? So what's the point in super-expensive portable players like the Acoustic Research M2?

Well, if you've spent a good chunk of cash on some quality headphones, pairing them up with a high-end, high-resolution audio player can make a huge difference to your aural experience.

And the high-end headphone market is booming right now, with more and more people developing a penchant for quality, not just convenience, in their listening.

The cheaper option is to pick up a portable DAC and headphone amp to plug into your phone, to take on the heavy lifting duties of high-res audio playback. But daisy-chaining devices to your phone can be a right royal pain in the AAC.

The audiophile solution, then, is to bag a dedicated high-resolution player like the Acoustic Research M2.


No compromise

And the AR-M2 is all about audiophile-levels of performance, without compromise. Everything has been tuned specifically for sound quality above all else, from the customised Android OS to the Burr-Brown DAC to the hi-fi-quality amplifier inside that sturdy all-metal chassis.

In fact, Acoustic Research talks about the M2 more as a tiny high-end hi-fi system than a portable music player. And it's hard to argue with that view once you've spent any time with your ears being lovingly massaged by it.

Starting inside, Acoustic Research has opted for some of the finest audio components around. The Burr-Brown PCM1794A digital-to-analogue-converter is touted as the flagship DAC, and the Class A amplifier AR has used inside the M2 is equally highly regarded.

That amp is a perfect example of the no-compromise design route AR has taken here. Because it's a Class A amplifier it has a huge amount of power behind it, giving it the ability to drive even the most demanding of high-end headphones, and deliver astonishing sound quality too.

The M2 also has a dedicated 3.5mm line out connection to help it make the most of such a powerful amplifier.


But that also means the M2 demands a hell of a lot of power to keep it running, which is why AR has packed a hefty 4,200mAh battery inside, just to keep the music playing.

AR could have opted for a lesser, more energy-conscious amplifier, but such a compromising of the M2's audio chops, in exchange for a potentially slimmer chassis and longer operating life, wasn't worth it in light of what AR was creating.

Alongside the DAC and amp components, there's a middling quad-core Qualcomm Snapdragon 400 processor taking care of the digital duties, making sure the Android 4.3-based OS runs smoothly.

There's also a full 64GB of internal storage, with support for microSD expansion cards and OTG USB drives.

AR has also ensured that all the digital and analogue circuitry has been isolated, to ensure there's no potential for leakage.



As an audiophile piece of music gadgetry the M2 supports a huge range of audio formats. It's more than happy with a full 24-bit/192kHz FLAC file, there's ALAC, WAV and AIFF support as well as DXD, and both DSD64 and DSD128 capabilities too.

The rather old-school Android 4.3 OS has been customised for lossless audio playback, in that it gets cut completely out of the audio path when the M2 is running its own AR Music Player app. The application has its own dedicated high-res path, which completely eschews the Android operating system to avoid any audio issues the software might introduce.

There's also a second, generic audio path that deals with the standard Android audio framework for apps like Spotify, Qobuz and Tidal.

In terms of design, the glass front and all-metal chassis give the M2 a real sense of robustness, as well as a certain understated style. At 245g, though, it is a rather weighty and chunky device. You'll certainly know you're carrying the M2 in your pocket – and not just because of the soundscape you're walking around in.

But, when you're paying some £900 for an audiophile device, you want to feel like there's a serious weight of aural technology being secreted away inside your pricey new player.