Technology with Perfect Accuracy

Technology with a Single Purpose

A faithful re-creation of the original experience, beyond any numerical representation.

Audio quality is affected by a variety of different factors, and certain performance indicators demonstrate that a high level of quality has been achieved.

These performance indicators are not the entire story - many other factors also have a major impact on audio quality.

Based on the knowledge and experience gained in over 30 years of audio product development, VELVET SOUND's approach to audio technology is to treat both measured performance and the less easily quantifiable aspects of the listening experience as essential.

Technology with Perfect Accuracy

Perfect live sound,
made possible by perfect numerical accuracy

Is your listening experience faithful to the original?
An authentic listening experience must be free of added noise and distortion.
VELVET SOUND continuously improves performance and creates new technology in order to eliminate those distractions, revealing a world of real live sound.

Low-noise technology:

Reconstructing low-level signals with clarity

The AK4499EX has achieved an industry-best performance of 135 dB SNR.


In order to deliver noise performance that approaches the theoretical limit, it's important to have high matching accuracy among the many resistor elements used to generate current output.  The AK4499EX uses a new technology called DWA ROUTING to reduce the effect of element mismatch due to the manufacturing process. The resulting outstanding low noise performance makes it possible to accurately re-create low-level signals with perfect clarity, allowing for a wider range of audio expression.


*DEM --- Dynamic Element Matching ​

*DWA --- Data Weighted Average

Low Noise Technology

Reproduction of signals as quiet as -155dBFS – one 50 millionth of full scale.

Low-distortion technology

A more faithful re-creation

The AK4499EX's industry-best -124 dB THD+N was made possible by VELVET SOUND's low-distortion analog circuit technology, which has led to the development of many products that feature the industry's best low-distortion characteristics.


The elements used in semiconductor circuits are subject to various degradation factors which are the result of the manufacturing process.   AKM's low-distortion design methodology identifies and addresses these degradation factors, making it possible for the AK4499EX to achieve the industry's best ultra-low distortion performance among high-end DACs.


The near-elimination of distortion allows for playback that is completely faithful to the original sound experience.

Low Distortion Technology

Undesired components reduced to -124dB - a ratio of 1:1,500,000
A faithful re-creation of the original
Spectrum at 1kHz, 0dBFS input

Components other than the fundamental wave are suppressed.
THD + N (total harmonics other than the fundamental wave + noise integral value) -124 dB in the 20 kHz band is achieved.

Artifact-free technology:

More natural sound

The AK5578 / AK5572 achieve the world's smallest intermodulation distortion characteristic of 116 dB, in addition to a wide dynamic range of 121 dB (single-channel mode) to 130 dB (channel sum mode).

A music signal is comprised of multiple frequency components.  The generation of spurious tones due to the interaction of these components is suppressed by VELVET SOUND's low-distortion technology.

This leads to a high spurious-free dynamic range (SFDR), enabling more natural sound reproduction.

Serious Free Technology

Spectrum at 800Hz, 1kHz dual tone input
Intermodulation components such as 200Hz, 600Hz, and 1.2kHz are suppressed, and intermodulation distortion of -116dB is achieved.

Technology with a Single Purpose

A faithful re-creation of the original experience,
beyond any numerical representation.

There is sound beyond sound.  The sound beyond what our ears can hear is critical to the experience.
The experience is more important than the measurement.
AKM's years of experimentation have yielded a multitude of techniques to create sound that resonates, emotionally.
VELVET SOUND addresses every aspect of sound, building a world of authentic sonic experience.

OSRD Technology:

More expressive audio

Low out-of-band noise

AKM's OSRD (Over Sampling Ratio Doubler) has a signal bandwidth of approximately 200 kHz, which is 10 times the audible range (~ 20 kHz).

It is possible to achieve lower out-of-band noise in the frequency band beyond the audible range by increasing the OSR, but this comes at a price, as power consumption increases due to higher-speed operation.

OSRD technology eliminates this trade-off by allowing OSR to be increased without raising power consumption.
VELVET SOUND DACs have adopted this technology, resulting in ultra-low out-of-band noise. (Patented in 2016)

OSRD Technology

Plot of out-of-band noise at 1kHz, 0dBFS input
The noise floor up to about 200kHz is flat, enabling more broadband signal re-creation.

Layout technology:

Delicate and bold expression

VELVET SOUND's layout technology is built to honor the original signal content.

The noise resulting from the operation of switching digital circuits is reduced to the utmost degree.  All noise-mixing paths to the signal are eliminated.

Beyond just the audio content, the timing references are also thoroughly separated from noise sources, greatly improving noise rejection in the resulting audio signal.

VELVET SOUND devices use a fully symmetrical left-to-right layout.  Features such as channel-independent assignment of analog power supplies and signal reference terminals enable smooth and flexible signal flow.

This approach to layout and signal routing enables the most delicate and bold expression of sound possible today.

Sound color IRD filters:

More colorful sound

Everyone is aware of the importance of accurately conveying the signal waveform itself, but what about its transient response?

After much experimentation focused on the signal waveform, AKM has developed the IRD (Impulse Response-Designed) Filter, which allows the user to control the transient response of the signal.


In PCM mode, six types of digital filters enable music playback optimized for a variety of settings.


In PCM mode, four types of digital filters are available, enabling optimization for a variety of settings.

DAC: Sound Colors (Impulse Response Designed Filter) DAC: Sound Colors
ADC: Sound Colors (Impulse Response Designed Filter) ADC & SRC: Sound Colors

High resolution digital core:

Expression in even higher definition

The human ear can distinguish low-level differences in sound that may not appear in the measurement values of general audio instruments.

VELVET SOUND's 32-bit product line is equipped with a high-resolution digital core that has ben extended to 36-bits, enabling the re-creation of even the faintest sounds and a truly realistic high-resolution experience.

Dedicated listening room for sound validation

AKM’s listening room has been designed and filled with industry-leading components, allowing for the most thorough evaluation possible.

This allows AKM to fully assess the sonic qualities of our audio devices, beyond the traditional approach of using audio test equipment on a bench.

AKM’s Audio Meister evaluates new test chips for sound quality and feeds the results directly back to the circuit designers.
Designs are modified and test chips are sent back to the Audio Meister until he is satisfied with the results.

This listening room is also utilized to evaluate various digital formats in order to allow AKM to optimize our devices for every digital audio standard in the industry.

Audio Room Audio Room

Hardware in pursuit of musicality:

AKM Evaluation Boards

AKM’s engineers provide high-quality evaluation boards to allow assessment of the reproduced audio content in a state that is very close to that of a finished product.

In the service of musicality and rich sensibility, AKM has paid great attention to the layout, materials, and construction of these boards, along with carefully-considered component selection.

AKM’s DAC evaluation boards expect digital audio sources and power supplies to be provided externally, allowing the user to more closely simulate their system.

AK4499EX Sound Board AK4499EX Sound Board
AKD4490 Sound Board
AKD4493 Sound Board
AKD4497 Sound Board
AKD4499 Sound Board