Acoustic Research M2 (Discontinued)

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The AR-M2 is a high resolution portable music player with a custom android user interface offering a familiar user experience. The UI is easy to use and gives almost instant access to your favourite music. Featuring a high quality DAC and other reference grade internals the AR M2 can power even the most demanding headphones.

The revolutionary Acoustic Research M2 Music Player brings the music listening to a whole new level. Through the flagship grade Burr-brown PCM1794A DAC and best-in-class high slew rate headphone amplifier, it is capable to unleash the full potential of your high resolution music clips through high end headphones without the need for an external headphone amplifier. This is the all-in-one product you need for genuine audiophile music experience on-the-go.

Features
Genuine audiophile oriented music-only portable music player
Comprehensive high resolution media support (WAV, AIFF, FLAC, ALAC, APE, DSD, and DXD)
Audiophile oriented flagship class Burr-Brown PCM1794a DAC
Unleash the full potential of high end headphones with best-in-class built-in headphone amplifier
64GB built-in memory plus flexible storage expansion through Micro SDXC
Up to 9 hours of continuous audiophile-grade high resolution music playback

Key Features of the M2
Flagship Class Burr-Brown PCM1794A Current Output DAC
Future-proof High Performance Quad Core Processor
Unique high-current high-output Class A based amplifier
Audiophile-grade analogue volume ALPS potentiometer
Line-out to feed a Hi-Fi system
Phenomenal Signal to Noise Ratio & Dynamic Range

Quote: Arex Li - Designer of the M2
"We started with raw audio performance, then a powerful headphone amp and only then did we add the features"
5 inch OGS HD IPS colour display screen
Easy-to-use Multi-touch “MusicSurf” GUI 
Android OS base, tuned for pure music
Pure Lossless Audio Path bypassing Android OS totally
High capacity battery 4000 mAH - 9hrs average battery life
Duralumin metal housing - tough and good-looking
Unlimited expansion via Micro-SXCD cards
Full Wi-Fi streaming capability

Remarkably compact for a high-end player
136.5 h x 71.1 w x just 15 mm deep
Weight 245 gms

Flagship DAC Performance Ratings
Burr-Brown PCM1794A Current Output DAC
2 x better than Burr-Brown PCM1795
2.8 x better than Cirrus CS4398 (PCM mode)
4 x better than Cirrus CS4398 (DSD mode)
2.8 x better than Wolfson WM8740 (Dual DAC mode, 1-ch per DAC)
4 x better than Wolfson WM8740 (Single DAC mode, 2-ch per DAC)

High-power high-precision current feedback headphone amplifier
High-power headphone amplifier
Power output (THD < 0.01%)
32 ohms 400mW + 400 mW 
300 ohms 43mW + 43mW
Ultra-low-distortion at max output <0.01%
Supports 16 ohms to 600 ohms headphones/earphones
Ultra high slew-rate, genuinely responsive to Hi-Res contents

High Performance Qualcomm Quad Core Processor
Plays virtually all Hi-Res audio formats including ALAC, FLAC, WAV, AIFF, 
Plus DSD64/DSD128 & DXD
Custom developed Hi-Res DSP processing
Wi-Fi wireless audio
NAS with DLNA support
64GB built-in memo
Micro-SDXC expansion Up to 400GB
USB OTG media playback support (TBD)
USB OTG Thumb Drive
USB Harddisk

Design Background
The acoustic & digital design of M2 was derived from AR's acclaimed desktop UA1 DAC, delivering real audiophile sound and Hi-Res playback on-the-go. Like UA1, the M2 features a dual-clock crystal oscillator design for native frequency support at all multiples. 

AR High-Res Music Player
The simple but comprehensive AR music player, plays music through the M2's proprietary Hi-Res Lossless audio path. Compared to other music player software for Android, it simply delivers better sound.

Battery Life
The linear/class A amplifier delivers best sound with the penalty of high power consumption. The solution in M2 is to  include a battery with double the capacity of most competition, to give about 9 hours of playback. On top of that, M2 is powerbank-friendly. Any 5V-2A Power Bank will power M2 for very extended music playback charge it simultaneously.

Heat dissipation
There are copper heat spreader shields on both sides of the M2 PCB and is dissipated quickly over the whole body of the  player. The copper heat spreader serves as RF shielding as well.

Memory expansion
On top of built-in memory, the M2 supports expansion through both micro SDXC (up to 400GB card supported) and  USB-OTG flash storage (e.g. Sandisk Ultra Dual USB).

Large screen for touch operation
Instead of building a thick brick, we put the battery and the audio circuit board side by side.  Although the player is bigger, it is slimmer. This is better for heat dissipation and allows the use of large screen for easy touch operation.

Why Android?
Android offers a good operating OS BUT the OS audio framework caused serious damage to sound quality for best sound the M2 has its' own High-Res audio Path that bypasses the OS, we decided to build a proprietary audio path for precision.  The AR music player played music through the proprietary audio path.  Compare to other music player software for Android, it simply delivered better sound.
Mature touch based interface
Mature wireless network support
Efficient media scanning (fast scanning of huge number of songs based on tags)
The M2 was designed to be more powerful than many portable headphone amplifiers, it is an excellent choice to show off high-end headphones on the go.