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Astell & Kern AK240 Stainless Steel DAC Digital Music & Media Player


Astell & Kern

Moon Audio

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Sold Out & Discontinued.

The AK240 Stainless Steel Edition takes the sound quality of the original AK240 up a notch.

The stainless steel takes advantage of the AK240’s features and allows you to experience a clear and more focused sound.

Android File Transfer - Move files from Apple Mac to AK Players



The stainless steel takes advantage of the AK240’s features and allows you to experience a clear and more focused sound.

Includes native DSD playback via Dual DAC setup and MQS Streaming.

Supported Audio Formats Include:  

WAV, FLAC, WMA, MP3, OGG, APE(Normal, High, Fast), AAC, ALAC, AIFF, DFF, DSF, FLAC, WAV, ALAC, AIFF : 8kHz ~ 192kHz (8/16/24bits per Sample) / DSD Native : DSD64 (1bit 2.8MHz), Stereo / DSD128 (1bit 5.6MHz), Stereo.

Is there a difference in sound?

Yes. The stainless steel chasis of the new AK240 solves the issue of grounding which is one of the factors that can dramatically affect the sound of your hifi equipment. The original AK240 has a limited ground area due to its Duralumin body. Stainless steel, being an inert metal, provides more ground points on a larger area leading to improvement in sound quality over previous iterations.

Includes new French Leather Case made from Tannerie Rémy Carriat that pairs well with this unique stainless steel edition of the AK240.

Native DSD Support, What is DSD?

DSD (Direct Stream Digital) is a digital audio file format originally developed for SACDs (Super Audio CD). Regular digital audio file formats such as PCM (Pulse Code Modulation) is separated into 65,000(16bit) to 16,700,000(24bit) of information on the Y axis, and 44,100(44.1kHz) to 192,000(192kHz) across the X axis for digital signals. DSD files have 1bit (0s or 1s) for Y axis and is separated into 2,800,000(2.8MHz) to 5,600,000(5.6MHz) of information for X axis.

Compared to regular audio CDs with 16bit/44.1kHz PCM format, SACD’s recording frequency goes up to 100kHz and the dynamic range goes beyond 120dB while maintaining sound clarity during the transmission.

Native DSD Support

One of the approaches Astell & Kern decided that would help them move a step closer to the original sound quality was to provide native DSD playback without having to convert it into PCM. This was indeed a difficult task. In order to provide native DSD playback on the AK240, they had to select a different DAC chipset. Making the decision to change the DAC was not easy, but in order to reach that goal, they had to make a bold move which was to start from scratch.

Astell & Kern asked themselves: Does the DAC support Native DSD? 
Will it allow for the Dual DAC setup? What else is needed for the perfect Native DSD support?

In order to answer these three questions, Astell&Kern have decided to use the Cirrus Logic CS4398 chip in the Dual DAC setup with an added exclusive XMOS chip that will allow for Native DSD support.

The process of setting up Native DSD support was not an easy task. Since the main CPU does not process Native DSD, Astell & Kern needed a chip that will work with it.  It took a long time, but A&K made it work. Through countless hours of testing, Astell & Kern was able to achieve Native DSD playback by having the main CPU process the data, send it to the exclusive XMOS chip, then through the DAC to deliver the sound.

Balanced Output: Unbalanced vs. Balanced Output

The unbalanced method is the most commonly used basic method which consists of “left and right signals + ground line”. This setup includes a ground line which blocks out external noises from the outside. However, since the ground line cannot block out all of the external noises completely, external noises can be mixed into the signals that are transmitted, which then result in changes to the sound. The longer the signals travel, the more external noises that will be mixed into the sound which is why it is used within a short distance of 1 to 2 meters.

Unlike the unbalanced method, the balanced method has an additional cold signal to compliment the hot signal which reduces the external noises.

Since the ground line cannot block out 100% of the external noises, noise will appear on both the hot and cold signals. The alignment of the 2 signals allows the noise to usually appear at similar points where they will eventually be removed as the signals are transmitted.

Dual DAC meets Balanced Output

It did not take Astell&Kern long to figure out that the AK240’s Dual DAC and balanced output resulted in the best sound. During the development of the AK100 and AK120, Astell & Kern's specific analogue amp setup was already creating full balanced analogue signals streaming from the DAC and they were able to move a step closer towards the original sound by then creating a balanced output terminal at the end.

256GB of Massive Storage

Astell&Kern has created the AK120 Titan with a storage capacity of 128GB, but in order to support Native DSD, MQS, and massive audio files, we had to come up with the ultimate portable music player with 256GB of storage.

With 256GB of internal memory, about 2,500 MQS (24bit/96kHz, 4 minute-long, 90MB) songs can be saved.  With the addition of a 128GB microSD card, the AK240 can support up to a total memory capacity of 384GB.

MQS Streaming

Astell&Kern products have started to evolve into network players by providing Wi-Fi capability.

To listen to your favorite music, you no longer have to turn on your computer, search for your music, wait for the songs to download, connect your player via USB cable, and then wait for the files to transfer to the player. Now with MQS Streaming, you can easily download or stream music directly from the AK240 by having the unit and your computer connected to the same network.

- "Astell&Kern MQS Streaming Server" software must be installed on your PC or MAC with a shared folder saved for MQS Streaming to work.

OTA (Over-The-Air) Upgrade

It has been 13 years since iriver has used the term "firmware". Through these years, one had to check for new firmware updates by opening emails or checking the website. Now with a Wi-Fi connection, you can receive instant notifications about new firmware updates and can update your unit whenever and wherever you are.

More Detailed 10-Band 0.5dB-step EQ Setting

More accurate EQ setting is also available on the AK240 by doubling the bands (from 5 to 10 bands) and halving the dB steps (from 1dB to 0.5dB) available. One can also create and save customized preset EQ settings to fit various music genres.

Full Touch Screen

Compared to the AK120, the 3.31 inch AMOLED display on the AK240 is about 82% bigger to provide more information at a glance. With the bigger display, the Full Touch screen makes it easy to navigate especially for smart phone users, and iPod™, iPhone™, iPad™ users.

The playback and volume control buttons have been upgraded on the AK240. Music tracks with long titles, such as a classical music, are displayed on 2 lines for better navigation. Due to the speedy file scanning functionality, a separate DB scanning function is no longer needed and file search is available for easy access to music.


The AK240 supports Native DSD USB DAC function. (DoP method)

Through the USB connection, the AK240 can be used as a USB DAC which supports Native DSD playback. The combination of the exclusive DSD chip and the Dual DAC in the AK240 goes above and beyond most computer sound cards and is able to create a greater sense of space and deeper sound while listening to your music.  

*- EQ setting cannot be used while in USB DAC mode on the AK240.

Differences between the 3 top tear models

AK100 II – Single Cirrus Logic CS4398 DAC (converts DSD playback to PCM), lower output from single ended & balanced output (1.7vrms single ended, 2.0vrms balanced), 64gb internal memory, body is not scratch resistant, 3150 Li-Polymer battery

AK120 II – Dual Cirrus Logic CS4398 DAC (converts DSD playback to PCM), same power output as the AK240 (2.1vrms single ended, 2.3vrms balanced), 128gb internal memory, body is not scratch resistant, 3250mah Li-Polymer battery

AK240 – Dual Cirrus Logic CS4398 DAC with XMOS Sound Processor for Native DSD playback up to DSD128, 256gb internal memory, duralumin scratch resistant body with real carbon fiber back plate, 3250mah Li-Polymer battery

AK240 Instruction Manual


Have Additional Questions?

Find answers to common questions on our guides.



Additional Info

Dual Cirrus-Logic CS4398 DAC allows Bit-to-Bit Native DSD audio playback.

Housing made from aircraft grade Duralumin, back cover is comprised of true Carbon Fiber.

Unbalanced & S-PDIF audio output through 3.5mm jack & Balanced audio output through 2.5mm 4-Pole TRRS jack.

New user interface for the AK240: faster & more intuitive.

Full external USB/S-PDIF DAC support.

256GB of internal flash memory, single micro SD card slot (supports up to 64GB): total possible storage of 320GB.

Increased screen size: 3.3” 800x480 AMOLED full touchscreen.

Stream MQS audio from your computer & download music straight to the AK240 from hi-res audio content providers via Wi-Fi.

Upgrade system software via Wi-Fi OTA (Over-The-Air).

10 band adjustable user EQ settings and PRO EQ preset.



Cirrus Logic CS4398 x2 (Dual DAC)


Support up to 24bit/192kHz Bit to Bit Decoding, DSD64/128


USB Micro-B input (for charging & data transfer (PC & MAC)) / Connection Mode : MTP (Media Device)


PHONES (3.5mm) / Optical Out (3.5mm) / Balanced Out (2.5mm, only 4-pole supported)


802.11 b/g/n (2.4GHz)



Body Color:


Body Material:

Stainless Steel


 66(W) x 107(H) x 17.5(D) (mm)

3.3 inch WVGA (480 x 800) AMOLED touch screen



Supported Audio Format:

 WAV, FLAC, WMA, MP3, OGG, APE(Normal, High, Fast), AAC, ALAC, AIFF, DFF, DSF, FLAC, WAV, ALAC, AIFF : 8kHz ~ 192kHz (8/16/24bits per Sample) / DSD Native : DSD64 (1bit 2.8MHz), Stereo / DSD128 (1bit 5.6MHz), Stereo

Unbalance 2.1Vrms / Balance 2.3Vrms (Condition No Load)

Frequency Response:

 ±0.023dB (Condition: 20Hz~20kHz) Unbalance & Balance / ±0.3dB (Condition: 10Hz~70kHz) Unbalance & Balance

Signal to Noise Ratio:

 116dB @ 1kHz, Unbalance / 117dB @ 1kHz, Balance


 130dB @ 1kHz, Unbalance / 135dB @ 1kHz, Balance


 0.0007% @ 1kHz, Unbalance / 0.0005% @ 1kHz, Balance


0.0004% 800Hz 10kHz(4:1) Unbalance / 0.0003% 800Hz 10kHz(4:1) Balance

Output Impedance:

Balanced out 2.5mm (1ohm) / PHONES 3.5mm (2ohm)

Clock Jitter:

50ps (Typ)

Battery Capacity:

3,250mAh 3.7V Li-Polymer Battery


Built-in 256GB [NAND], External  1 x microSD (Max 128GB)

Supported OS:

Windows XP, Windows 7,8 (32/64bit), MAC OS X 10.7 and up


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