QLS Audio, HI-FI/HI-END Audio,DAC,WAV Player




QA660--SD Card WAV Hi-Fi Digital Audio Player

QA660--SD Card WAV Hi-Fi Digital Audio Player

Price: USD $550 (Exclude shipping cost)(Out of Stock)        How buy it: Click here       Warranty: Click here

QA660 is a Hi-End digital music transport developed for audiophiles with over 3 years development on the software and several major version upgrades on the hardware. This is a true competitor to most of the desktop Hi-End CD players, and able to boost the performance of your whole system with its’ ultra-high-fidelity digital output that ensured by the single threaded software framework, complicated power supply systems and 2 sets of sampling clock circuits.

Our target: Perfectly and accurately recovery for the music recordings, and deep dark background”.

The single threaded software framework

QA660 implemented the latest version of QLS-HiFi’s unique proprietary technology – the single threaded software framework. This technology ensured ultra-low jitters and high accuracy in playback of digital music, and set the new standards for the digital output of a digital music player at some points.

Why we spent over 3 years of hard work and several dozen thousands of cost in developing this software framework by creating several dozen thousand lines of completely new code from zero? Because we believe the primary task for a digital music player is high-fidelity sound recovery. QA660 is the result of our persistence in pursuit of our belief on HiFi.

The vital aspect of single threaded software framework is running different programs one by one in serial processing mode, and audio program is on the highest priority level. Anytime if the audio playback program calls for reading and decoding audio files on the SD card, the audio playback program overrides all other programs in running for the call right away. Once the audio data length decoded from the audio files reached a set point, this data segment then is sent to the I2S buffer automatically with overriding all other microprocessor commands. The microcomputer system reserves 200%more of the normal audio playback program running time from system for sending the audio data segment to the I2S buffer according to the precise calculation by our engineers. In order to providing enough time resource for audio playback program some other functions such as remote control are kept out from the main microprocessor, and carried by other independent chips. The whole process therefore providing a significant improvement in reducing jitters and streaming music data flow accuracy.

Support up to 24bit/192KHz wav files

The information of a 24bit/192KHz wav file holds is 5 to 8 times to the normal 16bit/44.1KHz CD format, thus the sound quality of 24bit/192KHz wav files is far beyond traditional music CDs regardless of the soundfield, density, dynamic range and resolution.


  • Streaming music data flow from the SD card to the digital outputs with Ultra-low jitters and high accuracy by the single threaded software framework together with 2 sets of independent sampling clock circuits (44.1K/44K) and mono-system-aspect-design in separated power supply systems and grounding systems.
  • Audio format supported:
      - WAV         :   16/24bit, 44.1~192 kHz.
      - FLAC       :    16/24bit, 44.1 kHz~48 kHz, compression level 0~8.
      - APE         :    16 bit, 44.1 kHz, compression level fast and normal.
      - WAVPack  : 16 bit, 44.1 kHz, compression level fast mode and high quality.
      - MP3         :    16bit, 44.1/48 kHz, 96k bps~320k bps, CBR/VBR/ABR encoding.
      - CUE         :    ANSI / UNICODE / UTF-8 Encoding.
  • Digital Output:(outputs can be used at the same time without interfering each other)
      - I2S/IIS
      - Optical
      - EBU/AES
      - RCA Coaxial
      - BNC1 Coaxial
      - BNC2 Current Mode Coaxial(needs a 75Ω ground resistor to convert the current signal to voltage signal so the DAC catches the digital input, some DACs may not have this resistor)
  • Support SD/SDHC/SDXC up to 128GB SDXC with FAT32 (upgradeable with further firmware upgrade)
  • OSD supports English, simplified Chinese and traditional Chinese.
  • Support Software(Firmware) Upgrade.
  • Output voltage: Coaxial (0.5V p-p), XLR (5V p-p balance)
  • Digital output formats: PCM / Dolby Digital / DTS
  • Total hamornic distortion: < 0.00002% @ 20-20k Hz
  • Dynamic Range: >140dB
  • S/N ratio (unweighted):>140dB
  • Power: 9-11W
  • Input Voltage: AC 110V and AC 220V selectable
  • Dimensions: 290x240x90mm (11.4" x 9.45" x 3.54") (with all the sockets)
  • Package weight: 3.6kg
  • Package Dimension: L440 X W300 X H130mm(17.3" x 11.8" x 5.12")

     Tips: The USB port is reserved for future upgrade, it's not functionable on QA660

QA660--SD Card WAV Hi-Fi Digital Audio Player
QA660--SD Card WAV Hi-Fi Digital Audio Player
QA660--SD Card WAV Hi-Fi Digital Audio Player
QA660--SD Card WAV Hi-Fi Digital Audio Player
QA660 Remote:(internal AAA battery is not included)
QA660--SD Card WAV Hi-Fi Digital Audio Player
Internal PCB board:
(In order to improve the quality and sound quality, components are subject to change without notice.)
QA660--SD Card WAV Hi-Fi Digital Audio Player

The following items are included with your Order:
  QA660 Player *1
  Remote Control * 1(not include AAA battery for remote control)
  Power cable  *1
 16GB Class10 SDHC Card *1
SDHC SD USB 2.0 Memory Card Reader *1 (Card Reader not Warranty)
  50cm IIS Cable *1

English User Guide *1

Price: USD $550.00 (Exclude shipping cost) (in Stock)

At the time of purchase, please indicate the following:
Your couftry's voltage specs

Payment methods 1: Direct remittance to PAYPAL   , Our paypal account: cxqmcu@cxqmcu.com

QA660 Player (Exclude shipping cost) USD $550.00     


Add QA100 Full Digital amplifier(add 1 items free shipping)  USD $389.00    


Shipping by DHL/EMS Express to United StatesCanada、JapanAustralia、India、Indonesia、KoreaMalaysia、New Zealand、Singapore、Thailand USD $50.00   


Shipping by DHL/EMS/EUEXP Express to all European countries and Brazil、Israel、Kazakhstan、Russia USD $70.00   
If the list have not include your country , Please send email to cxqmcu@cxqmcu.com 
or   clark_chen@yahoo.cn  and ask .  


Tip:  We will send good by DHL/EMS Expres, and we will declare the sending for gift with a low value(For example: USD $100.00), to reduction reciever side to pay tax or try to avoid reciever side to pay tax.

If the list have not include your country, Please contact us for get your shipping by E-mail.

Email address: 
cxqmcu@cxqmcu.com    clark_chen@aliyun.com    315392961@qq.com

Payment methods 2: 
You can go directly to our EBAY purchased online stores, and its Web site is:


Payment methods 3:  You alse can pay to our bank accout:

Our Bank Account(Need add pay banking fee USD $25.00, You need pay total price is: Prodiuct total price+Shipping +USD $25):

Beneficiary Account No: 179661616833
Beneficiary Name: CHEN XUEQIAN
Beneficiary Bank:HSBC Hong Kong
Bank Address: Head office 1 Queen's Road,Central Hong Kong    
Bank Code:

Tip: The beneficiary name should be CHEN XUEQIAN , Not is QLS Electronics.

After payment,please e-mail us the your recipient name recipient address、zip Code、 contact phone number.
Our Email address: 
cxqmcu@cxqmcu.com    clark_chen@aliyun.com    315392961@qq.com


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With more than 150 years of experience, Western Union is a global leader in money transfer services. It helps consumers and businesses send money quickly and reliably,only take 5 minutes to arrive.you can visit www.westernunion.com for more details.Also it is easy to find a close agent from this link: http://www.westernunion.com/info/selectCountry.asp and please click Find An Agent .

Here is my westernunion info:
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Familyname: Tang
Address: A4-1-3B,Qianlong Xinmao Garden,Longhua,ShenZhen,Guangdong,China
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After payment,please e-mail us The Sender's First Name, Last Name, Total Amount, Money Control Transfer Number and address on the payment sheet, so that we can track and get the payment.
Also Please tell to us the your recipient name recipient address、zip Code、 contact phone number.
Our Email address: 
cxqmcu@cxqmcu.com    clark_chen@aliyun.com    315392961@qq.com

1. What makes the digital transport QLS QA660 a winner even in comparison with some other double priced products?

1). The unique QLS-HiFi single-threaded program framework.

Most of the other digital music players are developed under ARM hardware platform and multi-tasks operation system such as linux to reduce cost. As we analyzed that normal multi-tasks operation systems lead to huge amount of jitter contents in the music data flow, and jitter contents lead to "no air", "not smooth" and "loss of detail". 

QA660 implements the unique QLS-HiFi Single-Threaded Program Framework that special designed for HiFi music playback. This framework puts the audio program on the highest priority level of the microcomputer system. Moreover, the microcomputer system reserved enough running time resource from the system for the audio program that is 200% more than its' normal needs. Thus reduced the possibilities of generating jitter content as low as possible, and built a solid base for music playback over a microcomputer system.

2). Two separated crystal oscillators for 44.1K/88.2K/176.4K and 48K/96K/192K.

QA660 employees 2 customized 1ppm ultra-low jitter TCXOs to provide 44.1K/88.2K/176.4K and 48K/96K/192K sampling rate. This design avoided the distortion of sampling clock waveform caused by non-integer frequency division, and reduced the jitter even lower. Using only one crystal oscillators to provide 44.1K/88.2K/176.4K and 48K/96K/192K sampling rate is very normal for low-end products.

3). Fine design on power supply for clock circuits.

Multi-stage linear voltage regulation circuits are implemented to supply the clock circuits, especially for the 2 TCXOs, each TCXO is fed by a "ultra-pure" power supply that generated by a combination of a remote sense amplifier circuit, a reference circuit and a discrete component voltage regulator with current booster circuit. Thus any mod for this part is unnecessary, and very few improvement can be seen even you do so.

A lot of DIYers tried mods such as replacing TCXOs, adding separated TCXO for 48K/96K/192K sampling clock, adding separated power supply for different part of the clock circuits,etc.. And a lot of successful stories have been heard by implementing the methods mentioned above. Most of those mods are for the low-end products. As a comparison, QA660 has a perfect power supply system in place already that a lot of DIYers once dreamed of.

4). Ultra-low high frequency noise.

In order to control the high frequency noise as much as possible, QA660 employees large-scaling sealed Toroidal Transformer with 3 separated secondary AC coils. Different function units of QA660 are sourced completely separated from the 3 secondary AC coils, and completely separated grounding system are utilized as well.

5). 4 layers PCB.

4 layers PCB is implemented on the audio board and master control board, and a full layer out of the 4 layers is used as ground layer. The integrity of the ground layer is very important to protect the integrity of high frequency signals and control the voltage ripple on the VDD pin of the chips, because the frequency of the 24bit/192K signal is over 10MHz. Any voltage ripple over 1mV on the VDD pin of the chips was defined as design issue during the commissioning, and such kind of issue was led to PCB re-design. This QA/QC standard caused a lot of "back-and-forth" for the final PCB design, and we believe that's worth it.

6). Conclusion

A perfect product is always born from hard works that never ignore every details. "Perfect Playback" is our goal and mission, and we never compromise for that purpose.


2.Why HiFi players do not like multi-task operating systems(Linux, Windows etc.)?

All the modern operating systems are designed for time-sharing and multi-tasks by implementing process scheduling and interrupt scheduling. In order to access the hardware at the very bottom, all the applications have to queue up under the control of the two level scheduling. Most of the operating systems use 100Hz tick rate so it takes at least 10ms for any programs to get scheduled. Moreover, due to large amount of programs running in the system, the audio interruption normally running in lower priority than network interruption and display/video interruption. All the programs in the scheduling queues are managed by the priority level, programs marked at higher priority level can interrupt the programs at lower priority level anytime even the low priority program is running, whenever there is a call from the higher priority programs, the low priority programs hold and wait as long as the higher priority programs completed. As a result the audio programs produce huge amount of jitters when the operating system holds the audio programs, and let the higher priority level programs such as network and display programs running. This is the major reason that CDP is always far better than PC-HiFi.

Any digital music player developed under a linux or whatever else multi-tasks operating system should be seen as a mini PC-HiFi.

As you can see a lot of HiFi USB DACs use big memory buffer to cache couple of seconds audio data in the design even with asynchronous USB interface. This fact is the evidence that the designers of those USB DACs do not trust the real time audio data flow handling by the operating system.


3. What are the improvements that QA660 has made in comparison with the first generation (QA550 or QA350)?

1). The biggest improvement is on the sound quality. In contrast with the first generation's portable style design, QA660 is a desktop music digital transport, and the design team has definitely taken the opportunity on the physical size increment to improve the power supply systems, sampling clock circuits, PCBs and so on. That makes QA660 a great competitor in comparison with some other mid or high-end products in the current market.

2). QA660 supports up to 24bit/192K wave, as well as flac, ape, cue and mp3. As the contrast, the first generation only supports 16bit/44.1K wave.

3). QA660 has a way better display/operating interface than the first generation. As so much effort has been made to enhance the operating interface, it's even better than some mature operating system based music player.

4). QA660 has fixed the compatible problem with different types of SD card that normally found on the first generation.

5). QA660 provides sufficient digital output interfaces, such as I2S and three coaxial outputs with slightly different sound styles, thus provided different ways to play with


4. Why QA660 does not support hard drive, usb drive and Ethernet?.

1). The simple the best, and this is the iron rule for HiFi products. The more tasks the microcomputer needs to handle, the less CPU resource allocates to each task, and more jitters generate from the digital music player.

2). Multi-tasks operating system based PC-HiFi player is easy to integrate hard drive, USB and Ethernet, so is great for people who need the functionality and convenience. But if you care sound quality more than anything else, QA660 is our answer. Moreover, SD card is the most popular media card in the current market, and the price get cheaper and cheaper. For instance a 64G SD card is able to store thousands of lossless songs that is good enough for most of the enthusiastic fans.

3). QA660 is always a winner in our comparison test with a lot of mid-end CD players/transports. Our goal is aiming for the high-end range products, and that is the reason QA660 only supports SD card.


1. The images of the product are for your reference only, subject to the real product on sale.
2. Our company reserves the rights of altering the characteristics, specifications and design of the product so as to make constant progresses in the performance of the product. The detail of alteration is free from public notification.

Price: USD $550 (Exclude shipping cost)         How buy it: Click here      Warranty: Click here


ADD:Room A1502,NiuLanQian Building,MinZhi Road,LongHua Town,ShenZhen,GuangDong,China
Postalcode: 518131  TEL:0755-28187975    FAX:0755-28187976
E-Mail: cxqmcu@cxqmcu.com