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.
and accurately recovery for the music recordings, and deep
The single threaded software framework
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
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.
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
Support SD/SDHC/SDXC up to 128GB SDXC with FAT32
(upgradeable with further firmware upgrade)
OSD supports English, simplified
Chinese and traditional Chinese.
Dimensions: 290x240x90mm (11.4" x 9.45" x 3.54") (with
all the sockets)
Dimension: L440 X W300 X H130mm(17.3" x
USB port is reserved for future upgrade, it's not
functionable on QA660
AAA battery is not included)
Internal PCB board:
(In order to improve the quality and sound quality,
components are subject to change without notice.)
following items are included with your Order: QA660 Player *1
Remote Control * 1(not include AAA battery for
Power cable *1
16GB Class10 SDHC Card *1
SDHC SD USB 2.0
Memory Card Reader
50cm IIS Cable *1 English User Guide
Price: USD $550.00
shipping cost) (in Stock)
time of purchase, please indicate the following: Your couftry's voltage specs.
Payment methods 1: Direct remittance to PAYPAL ,
Our paypal account: firstname.lastname@example.org
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.
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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
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
4). Ultra-low high frequency
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
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.
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.
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
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
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.
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.