About Us

Qudelix is an audio system engineering company.

We deliver portable and affordable high-end audio solution for everyone. Based on the highly extensive background and experience of our R & D team, we design and implement the cost-effective high-end audio system. In a digital audio system, System-on-Chip (SoC) is one of the most important keys to the best product. We always keep up with the latest semiconductor technology and build the best application with optimized software and hardware.

Sony’s LDAC™ Official Technical Partner

As an Official Technical Partner of Sony's LDAC, we developed the LDAC solution for Qualcomm QCC512x platform, which is the best-in-class SoC for high-end Bluatoother application.

LDAC is a Bluetooth Audio Codec, which provides the best sound quality over the other codecs. Every Android device with Oreo or higher supports LDAC by default. Currently, over 38% of the total Android devices support LDAC, and the numbers are getting increased 

On the other hand, LDAC sink or receiver application does need Bluetooth SoC. QCC512x, the latest technology of Qualcomm, is the most advanced Bluetooth SoC, which is the best fit to LDAC receiver. QCC512x's ultra-low power consumption and the most powerful DSP capability enable the application devices to maintain high bitrate LDAC streaming more secure and for longer time.

We developed the LDAC solution for QCC512x SoC and support worldwide set makers integrate LDAC on their QCC512x applications. 

Please contact support@qudelix.com for further information.

*LDAC and LDAC logo are trademarks of Sony Corporation.


Qudelix-5K Reference DAC/AMP

  • Qualcomm QCC5124 Bluetooth System-on-Chip
  • Dual ES9218P SABRE HiFi® DAC
    • 3.5mm Unbalanced output max. 2.0V RMS 
    • 2.5mm Balanced output max. 4.0V RMS
  • aptX Adaptive, LDAC, AAC, aptX-HD, aptX, SBC
  • 500mA Battery
    • Max. 20 hours streaming (AAC Standard 1V RMS mode)
  • High-Resolution USB DAC 96KHz / 24-bit
  • 10-band Double Precision PEQ/GEQ
  • High Sensitivity 3-dimensional LDS Antenna
  • Qualcomm® cVc™ noise cancellation technology
    • High Sensitivity MEMS Microphone
    • Earphone Inline Remote/Mic. Support
  • Companion mobile app iOS/Android

Qualcomm QCC5124 

The new Qualcomm® Low Power Bluetooth SoC QCC5100 series is designed for advanced Bluetooth application. The breakthrough SoC series is engineered to reduce power  consumption by up to 65 percent for both voice calls and music streaming, compared to previous CSR8675 solution. It is designed to reduce power consumption dramatically and offers enhanced processing capabilities.

Qudelix-5K is the world 1st Bluetooth DAC/AMP designed with QCC512x chipset. QCC512x's ultra-low power consumption and the most powerful DSP capability enable Qudelix-5K to maintain high bitrate LDAC streaming more secure and for a longer time.

Bluetooth Audio Codecs

The Qudelix-5K is the world's 1st Bluetooth DAC/AMP to support all the latest codec technologies, including aptX Adaptive, LDAC, AAC, aptX HD, aptX Low Latency, aptX, and SBC.

aptX Adaptive is Qualcomm next generation dynamically adjustable audio codec designed to deliver robust, low-latency, low-bit rate, high quality wireless audio. *aptX and aptX-HD are also supported. 

For more Information : aptX Adaptive

Sony's LDAC™ is a new audio technology from Sony that allows you to enjoy high quality wireless audio via Bluetooth. With 3x the data transmitted, LDAC provides an enhanced wireless listening experience for all your music.

*LDAC and LDAC logo are trademarks of Sony Corporation. Qudelix is an official Technical Partner of SONY LDAC.

Advanced Audio Coding (AAC) is an audio coding standard for lossy digital audio compression. Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at the same bit rate.

Dual ES9218P

ES9218P is a high-performance 32-bit audio SABRE HiFi® D/A Converter with Quad DAC™ Technology, headphone amplifier, and analog volume control designed for the audiophile-grade application.

Qudelix-5K, integrated with two ES9218P, delivers the best in class sound quality. 

Four DAC modes

To provide more extended battery time, Qudelix-5K works with single ES9218P for the 3.5mm unbalanced output.

For the 2.5mm balanced output, dual ES9218P, one for each channel, deliver the doubled output voltage through the full differential direct signal path.

Also, users can limit the maximum output voltage to reduce extra power consumption and extend the battery time.

  • 3.5mm Unbalanced (single ES9218P)
    • 1.0V RMS mode (21H)
    • 2.0V RMS mode (16H)
  • 2.5mm Unbalanced (dual ES9218P)
    • 2.0V RMS mode (13H)
    • 4.0V RMS mode (9H)

*Quoted playback time based on using the AAC codec, 3.5mm unbalanced output.

8 x DAC Filters

Every Oversampling D/A Converter needs a digital low pass filter before D/A conversion. And the filters make the difference in sound signature, not the sound quality.

ES9218P provides eight different types of digital filters, and Qudelix-5K supports the users to select one of them for the best fit to their receivers and sources.

  • Linear phase fast roll-off 
  • Linear phase slow roll-off
  • Minimum phase fast roll-off 
  • Minimum phase slow roll-off 
  • Apodizing fast roll-off filter type 1 
  • Apodizing fast roll-off filter type 2 
  • Hybrid fast roll-off
  • Brick wall

Dual Precision Audio Clock

Qudelix 5K adapts dual MEMS oscillators, which deliver the best clock precision at lower power consumption than the conventional quartz oscillator.

USB DAC 96KHz / 24bit

Qudelix-5K supports 96KHZ/24-bit USB audio streaming. (No additional driver needed.)

You can have it charging and streaming at the same time with your PC or laptop while keeping the Bluetooth link with a smartphone and/or controlling every feature of Qudelix-5K through the companion mobile application. 

Any incoming sound alert or call ringing from smartphone will be automatically routed to Qudelix-5K, even when you listen to music through Qudelix-5K USB DAC.

Hybrid Volume Control with 0.5dB step

ES9218p has the built-in Programmable Gain Amplifier (PGA), which control the output level in the analog domain after D/A conversion. Qudelix-5K offers systemwide high precision 0.5dB step volume control capability through PGA and Digital Gain control, keeping the optimal sound quality even at the lower volume level.  Furthermore, with the companion mobile application, you can set other details on optimizing the listening environment to the best.

  • 0.5dB step Master Volume -60dB to 0dB with PGA and Digital
  • L, R Volume trim & offset control
  • Max. Volume limit option
  • Smart Volume Optimization for the best Signal to Noise Ratio

Clear Voice Call

Qudelix-5K, integrated with built-in MEMS microphone, supports Qualcomm® cVc™ noise cancellation technology. The MEMS microphone delivers 4~6dB higher performance than a conventional condenser microphone.

Qualcomm® cVc™ noise cancellation technology brings advanced audio enhancements and noise suppression to the near and far end, and provides packet loss and bit error concealment.

Laser Direct Structuring Antenna

Compared to small size chip antenna, LDS Antenna provides more space and length for better RF performance. 

Qudelix-5K adopts LDS antenna technology and offers enhanced RF performance.

Inline Microphone & Remote Control

Qudelix-5K support the inline microphone and remote control optionally. 

OTA(Over-The-Air) Firmware Update

The companion mobile app can update the Qudelix 5K F/W over Bluetooth Link.

DAC/AMP is no longer just a simple receiver or adapter, but an independent system that operates with complicated embedded software. We value our software and want to upgrade it together with the users. 


  • Plastic Body (Black) with anti-scratch UV Coating
  • Aluminium Clip (Dark Gray)


52.8(H) x 26.7(W) x 15.6(D) mm (including Clip)


Design Philosophy

We want the device to work as a universal DAC/AMP for both high-sensitivity IEMs as well as high-impedance open-back headphones. We want it simple, small, yet but powerful. In addition to the sound quality and the maximum output power, we also need to consider the battery time as well, concerning the nature of the device.

We've tried many DACs and Amplifier ICs and found ESS9218p is the best option for our goal. Besides the sound quality, the primary advantage of ESS9218p is that the built-in amplifier delivers the maximum output voltage up to 2V RMS. Furthermore, it supports the 1V RMS option at the same sound quality to save power consumption.

For high-sensitivity IEMs, the amplifier noise figure is the most important. The high-sensitivity IEM is so sensitive that it translates every electrical noise or thermal drift into audible acoustic sound, usually white noise.

On the other hands, the high-impedance headphones require a higher power amplifier. Those headphones usually have low sensitivity, and they are free from the white noise affected by the amplifier noise characteristics. Instead, they need higher power from the amplifier output to deliver enough loudness and headroom.

We designed the software and the app to provide full access to every internal option of ES9218p.

3.5mm Unbalanced (Single Ended)

1VRMS Mode

For the most IEMs, The 2V RMS output would be too much. The 1V RMS mode offers the best power efficiency at the same sound quality as the 2V RMS mode.

2VRMS Mode

For low sensitivity IEMs or headphones, the 2V RMS mode delivers enough headroom and loudness.

2.5mm Balanced (Full Differential)

2VRMS Mode

The full differential direct audio path delivers the best linearity and separation, still with enough battery time.

4VRMS Mode

The maximum output power


4 types of output mode:

  • 3.5mm Unbalanced with single DAC 1.0V RMS
  • 3.5mm Unbalanced with single DAC 2.0V RMS
  • 2.5mm Balanced with dual DAC 2.0V RMS
  • 2.5mm Balanced with dual DAC 4.0V RMS

To sum it up, Qudelix-5k offers a total of four DAC/AMP modes, and the users can trade-off the output power and battery time.


Dual-Core 32-bit KALIMBA DSP

QCC5124, the heart of 5K, embeds dual-core 32-bit KALIMBA DSP running at 120MHz. 

*CSR8675 has single-core 24-bit KALIMBA. 

Moreover, the new operating system for KALIMBA DSP enables the device to support more flexible and versatile audio processing capability.

User can control every setting through the companion iOS/Android mobile app, and the settings are controlled over BLE (Bluetooth Low Energy) link and stored in the device automatically once changed. The device stores all user settings internally and reloads them at the boot-up. 

Audio Source through Bluetooth A2DP or USB Audio Class is selected one at a time exclusively. The DSP processes the incoming source audio from Bluetooth or USB, based on the user configuration stored in the device. 

Qudelix-5K keeps the Bluetooth link with your smartphone, while connected to PC as a USB DAC. In this use case, the primary audio source is Bluetooth A2DP, and the secondary is USB. The internal logic selects the source automatically, upon the presence of any sound.

LDAC for QCC512x

We've developed the LDAC library for QCC512x by ourselves, upon the official technical partnership contract between SONY and Qudelix. It's the proof of the world-class R & D capability of our team, and we're very proud of that.

Every line of the LDAC software library is optimized for QCC512x platform and KALIMBA DSP architecture. The highly optimized LDAC library and the ultra-low-power QCC512x enables the LDAC streaming more secure and for a longer time.

20-Band PEQ/GEQ (64-bit double precision)

The embedded pro-grade equalizer is a vital benefit of 5K DAC/AMP over other similar products. It processes every incoming source audio from everywhere: Youtube, Apple Music, Spotify, iOS, Android, PC, Bluetooth(all Codecs), and USB.

For more degree of freedom, 5K DAC/AMP supports parametric EQ in addition to graphical EQ. The embedded DSP cores perform double-precision 64-bit EQ processing, providing the most accurate and precise frequency response even at low-frequency range.


The 5K companion mobile app would be one of the most crucial benefits over the other similar Bluetooth DAC/AMP devices.

In the home screen of the app, you can see and check the operating configuration of 5K at a glance. On each table menu, the users can fine-tune every option for the best sound quality or for the longest battery time.

In addition to GEQ, you can use PEQ to control every little tune over the professional-grade embedded equalizer. 5K is to be probably the world's 1st Bluetooth DAC/AMP supporting embedded PEQ.


Welcome to Qudelix-5K forum.


  • 2019. 10. 25 02:37 PM

AKM and ESS offer outstanding performance and Sound Quality. The Sound Signatures slightly differ from each other, but it's a matter of preference.

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  • 2019. 10. 25 02:37 PM

Sensitivity represents how efficiently the earphone/headphone unit can translate the electrical energy into the acoustic sound.

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