看到techradar网站今年2月对AR-M2的一篇详尽评测，分享一下。
Acoustic Research M2 review
Super-powerful, seriously pricey and sonically sublime.
OUR 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.
FOR
Fantastic sound quality
Good storage
Seriously loud
AGAINST
Slightly weak battery life
Awkward OS restrictions
Chunky and weighty
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.
Support
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.
The Acoustic Research M2 is probably the best thing we've ever had pumping music into our earholes.
There's a depth and clarity, a broad separation and a real sense of power and purpose behind the way the M2 delivers its audio experience. With a pair of quality headphones, like the OPPO PM-3s, you get a stunning level of sound quality.
That Class A amplifier enables the M2 to drive audiophile headphones with genuine power, something the cheaper Pioneer XDP-100R seriously lacks.
But while the AR-M2 is capable of delivering an almost transformative audio experience with the hardware and software at its disposal, that doesn't necessarily make it the be-all-and-end-all of portable music devices.
It sounds great, but it's by no means the perfect player.
The Android Jelly Bean OS is very much last-gen software, and the lack of access to the full Google Play Store does limit the M2's usability on that front. You can get a decent suite of audio apps installed, such as Spotify and Tidal, but it's all via the side door – you have to download the .apk files separately and side-load them onto your device.
It's a terribly clunky way to roll in these modern times.
And adding other playback apps to the device can seriously confuse it too. We've had instances where we've been playing a track using the AR Music Player, paused using the physical controls down the right-hand side, and then when we hit play it continued the last tune we'd been playing from the Tidal app.
Acoustic Research is still keeping the software updated – it's recently brought in gapless playback for its high-res audio app – but you're unlikely to see any Marshmallows adorning the M2.
Having those physical controls is a great bonus for the player, meaning there's no need to turn the screen on to skip, play or rewind tracks, but because they sit so far proud of the chassis they're very easy to press by accident when pulling the M2 from your pocket.
The analogue volume control is similarly easy to nudge in the pocket. In one direction that's slightly annoying but not a huge problem; in the other the power of the M2 means you can end up really battering your eardrums.
Battery life is a bit of a struggle for the M2. It may have that 4,200mAh battery, but the powerful amp really does demand a lot from it, and as such you'll be lucky to hit the nine hours of audio playback AR promises; it needs a fair while to charge back up too.
We liked
It really is all about the audio when it comes to the Acoustic Research M2. All other considerations were obviously secondary when it came to designing this audiophile portable player – which is quite a refreshing stance.
And, given the quality of sound you get out of it with a pair of good headphones, AR's single-mindedness is almost entirely justified. Going back to my phone, or even another high-res player, after the M2 is an aurally disappointing experience.
The bountiful internal storage is impressive, as are the microSD and OTG USB expansion facilities, and the supreme power of its output doubly so.
We disliked
It's really not the most user-friendly of players. The Android OS is familiar, but the necessary side-loading of audio apps is a frustration. And while the AR Music Player, with its own lossless audio path, delivers great sound, it's not a particularly attractive or intuitive application.
Then there are the easily-pressed-in-error physical buttons. They sit far too proud from the metal chassis, as does the analogue volume control, which we often found got nudged when we dropped it into a coat pocket.
The battery life is a touch lightweight too, mostly thanks to that behemoth of an amplifier chewing through the beefy 4,200mAh battery. The device itself though is definitely not lightweight, and has a serious heft to it.
Verdict
As much as the Acoustic Research M2 is probably the best-sounding device I've ever plugged headphones into, there are some definite issues which stop me from giving it a resounding recommendation.
Obviously the price is pretty staggering, but then there is a wealth of high-quality componentry inside the M2.
I love the sound, but throughout my time with the M2 I kept finding myself going back to the Pioneer XDP-100R. It doesn't sound as good, but it's a more long-lived, more versatile and more convenient device.
The M2, though, is all about the audio – and if you are too then you'd have to look long and hard to find another device which sounds this good.
Acoustic Research M2 review
Super-powerful, seriously pricey and sonically sublime.
OUR 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.
FOR
Fantastic sound quality
Good storage
Seriously loud
AGAINST
Slightly weak battery life
Awkward OS restrictions
Chunky and weighty
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.
Support
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.
The Acoustic Research M2 is probably the best thing we've ever had pumping music into our earholes.
There's a depth and clarity, a broad separation and a real sense of power and purpose behind the way the M2 delivers its audio experience. With a pair of quality headphones, like the OPPO PM-3s, you get a stunning level of sound quality.
That Class A amplifier enables the M2 to drive audiophile headphones with genuine power, something the cheaper Pioneer XDP-100R seriously lacks.
But while the AR-M2 is capable of delivering an almost transformative audio experience with the hardware and software at its disposal, that doesn't necessarily make it the be-all-and-end-all of portable music devices.
It sounds great, but it's by no means the perfect player.
The Android Jelly Bean OS is very much last-gen software, and the lack of access to the full Google Play Store does limit the M2's usability on that front. You can get a decent suite of audio apps installed, such as Spotify and Tidal, but it's all via the side door – you have to download the .apk files separately and side-load them onto your device.
It's a terribly clunky way to roll in these modern times.
And adding other playback apps to the device can seriously confuse it too. We've had instances where we've been playing a track using the AR Music Player, paused using the physical controls down the right-hand side, and then when we hit play it continued the last tune we'd been playing from the Tidal app.
Acoustic Research is still keeping the software updated – it's recently brought in gapless playback for its high-res audio app – but you're unlikely to see any Marshmallows adorning the M2.
Having those physical controls is a great bonus for the player, meaning there's no need to turn the screen on to skip, play or rewind tracks, but because they sit so far proud of the chassis they're very easy to press by accident when pulling the M2 from your pocket.
The analogue volume control is similarly easy to nudge in the pocket. In one direction that's slightly annoying but not a huge problem; in the other the power of the M2 means you can end up really battering your eardrums.
Battery life is a bit of a struggle for the M2. It may have that 4,200mAh battery, but the powerful amp really does demand a lot from it, and as such you'll be lucky to hit the nine hours of audio playback AR promises; it needs a fair while to charge back up too.
We liked
It really is all about the audio when it comes to the Acoustic Research M2. All other considerations were obviously secondary when it came to designing this audiophile portable player – which is quite a refreshing stance.
And, given the quality of sound you get out of it with a pair of good headphones, AR's single-mindedness is almost entirely justified. Going back to my phone, or even another high-res player, after the M2 is an aurally disappointing experience.
The bountiful internal storage is impressive, as are the microSD and OTG USB expansion facilities, and the supreme power of its output doubly so.
We disliked
It's really not the most user-friendly of players. The Android OS is familiar, but the necessary side-loading of audio apps is a frustration. And while the AR Music Player, with its own lossless audio path, delivers great sound, it's not a particularly attractive or intuitive application.
Then there are the easily-pressed-in-error physical buttons. They sit far too proud from the metal chassis, as does the analogue volume control, which we often found got nudged when we dropped it into a coat pocket.
The battery life is a touch lightweight too, mostly thanks to that behemoth of an amplifier chewing through the beefy 4,200mAh battery. The device itself though is definitely not lightweight, and has a serious heft to it.
Verdict
As much as the Acoustic Research M2 is probably the best-sounding device I've ever plugged headphones into, there are some definite issues which stop me from giving it a resounding recommendation.
Obviously the price is pretty staggering, but then there is a wealth of high-quality componentry inside the M2.
I love the sound, but throughout my time with the M2 I kept finding myself going back to the Pioneer XDP-100R. It doesn't sound as good, but it's a more long-lived, more versatile and more convenient device.
The M2, though, is all about the audio – and if you are too then you'd have to look long and hard to find another device which sounds this good.
