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Portable Headphone DAC/AMP

  • 11 selected OP Amps in the analog section + 8 dual-current transistors.
  • Completely different from the battery circuit of the portable
  • Power circuit design that is lower than battery noise
  • Four 3300mAH Panasonic batteries provide a total battery capacity of 13200mAh
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Vendor: Quloos



Vendor: Quloos



High-End Mobile Design: This all-in-one device is designed with a high-capacity battery and power standards akin to high-end desktops, ensuring exceptional performance on the go.

Advanced Power Supply: With dual 1000000uF low internal resistance super capacitors, it offers isolated power supplies for both digital and analog components, similar to a desktop dual transformer setup.

ersatile Amplification: It features a balanced amplifier capable of outputting over 20V for driving high-impedance headphones, as well as a final stage power tube with a 2700mA current output for low-impedance, low-sensitivity headphones.

Comprehensive Connectivity: Equipped with an ES9038PRO DAC chip, ALL To DSD support, dual femtosecond crystal designs, Bluetooth input, USB interfaces, and multiple headphone ports, it ensures versatile connectivity and top-notch audio performance.

From the first limited edition product QA360LE released by QLS fiver years ago to the introduction of the second limited edition today, Clark has been improving the product 's sound quality during use this standard version. If the improved sound has achieved the level that he couldn’t wait to share, we might launch the modified edition in the market. Since Clark has been using some non-mass production techniques with low efficiency, we have to use more human resources and only provide limited products, in order to maintain high-quality sound.

Two years after the QA390 standard edition released to the market, the QA390LE (limited edition) emerged. Although it is coincidental and lucky that we can make such great sound improvements, we will definitely deliver more mature products with better sound effect through the long-term try and modify of Clark.

What does the limited edition upgrade?

Global Clock

Upgrade to AS338, the jitter has been reduced from 88fs to 38fs, thus greatly improving low-frequency quality in hearing, providing impressive and majestic low-frequency heavy sound..

Alternative DAC

The AK4497 that has halted production is replaced by ES9038PRO. Due to the honing more than a year, the alternative chip can bring excellent sound quality and audio experience.

Upgraded Bluetooth

It is compatible with more encoding formats. Through optimized design, the AS338 global clock is used to recollect data. After upgrade, the sound input through Bluetooth is better than the internal SD card played by the standard edition.

Power Optimization

It compensates the frequency bandwidth of super-capacitor, reduces the power supply internal resistance, and increases the power isolation of digital circuit and analog circuit, to improve the dynamic feature, ductility and permeability of sound.

Analog Circuit

It optimizes analog circuit design and component selection again, further improves sound density and details, and provides more open sound scenes and better sound with sense of depth, stereo and space.

Readjust sound

It collects feedback concerning the standard edition, and conducts a second toning to make the sound more complete. It focuses on the musicality, freshness, true nature and fullness of music, and ensures that music can be listened to for a long time without being annoying.

The sound of the limited edition is not the simple upgrade of that of the standard edition QA390, It’s more like a brand new product with completely different sound levels. The limited edition provides fresh sound with first-class musicality. Its full and heavy mid-low frequency sound is rather impressive. The exquisite sound effects make people feel like being in a concert scene.. Most importantly, it can present the sound with great momentum and dynamics that seemingly do not match its appearance. It’s a device that can enable people totally lost in music.

Power circuit design that is lower than battery noise

The noise of this chip is only 0.8μVRMS, which is much lower than the noise when the battery is working (the noise is about 2.7uV when the 3.7V lithium battery has a 500mA load). At the same time, the chip has a low frequency of nearly 100dB and a high of 76dB at 1MHz. The power supply ripple rejection capability eliminates interference from power supplies.

Can be used as a relative reference standard for ideal sound

Unconstrained by the volume, the battery generates a set of desktop-level isolated regenerative power supply, which solves the problem that the traditional AC power supply is affected by the power environment, making the sound more stable and stable, so that all users can hear the sound we want to express.

The QA390's battery-powered sound is largely unaffected by any external factors and is ideal as a relative reference for good sound.

Two super capacitors, supplemented by multiple isolated ultra-low noise power circuits

Dual 1000000uF low internal resistance super capacitor support for digital and analog partial isolation power supply, similar to desktop dual transformer design

Completely different from the battery circuit of the portable

Most of the batteries used in portable players are limited to 2 ~ 3A, which makes the sound scale, dynamic and momentum less natural than desktop players. The battery used in the QA390 can achieve a single discharge current of 10A, and we use multiple parallels to further reduce the internal resistance while the current capability is several times. This current explosive force exceeds many machines that use 220V power supply.

In addition, the analog and digital inlets of the power supply circuit each have a 1000000uF super capacitor, which provides further protection for the instantaneous current. The built-in very good power supply system is the basis of its good sound.

Programmable analog potentiometer volume control solves left and right imbalance and digital loss

Lossless analog volume adjustment ensures good sound quality at low volume: the adjustment range is wide, the adjustment process is very thin, and the left and right channels are almost completely balanced, thus achieving a wide range of precise control of the volume.

The pursuit of good sound is also reflected in every detail, QA390 uses the PGA2311UA with higher price and lower distortion rate instead of PGA2311U.

technical specifications
Internal playback storage
Use an external SD card or TF card plus card sleeve in FAT32 format, currently supports a maximum capacity of 512GB(Sandisk TF or SD card is recommended)
Internal playback support
16 - 32Bit, 44.1KHz ~ 352.8KHz, DSD64 ~ DSD128.
USB interface
  • USB B port: use the authorized Combo 384, support 32Bit / 384KHz PCM and DSD256
  • Micro port: use SA9227 interface, Apple phone and tablet do not need camera kit, support 32Bit / 384KHz PCM and DSD128
Bluetooth 5.0, supports HD Bluetooth up to 24Bit / 96KHz
Coaxial input
75Ω matched impedance, support 24Bit / 192KHz and DSD64(DoP)
Optical Input
Supports 24Bit / 192KHz and DSD64(DoP)
Coaxial output
0.5Vp - p75Ω, support 24Bit / 192KHz and DSD64(DoP)
Optical output
Support 24Bit / 192KHz and DSD64(DoP)
Analog output:
  • Frequency response: 20 - 20KHz
  • S / N: 122dB
  • Dynamic range: 121dB
  • Stereo Crosstalk:120dB
  • THD+N:0.0005%
Output level:
  • RCA (L&R) 2.5V (closed pre-amp)
  • XLR (L&R) 5.0V (closed pre-amp)
  • SE (Unbalanced)maximum 10.5Vrms(High amp voltage, Ultra high gain, 600Ω load)
  • BAL(Balance)Maximum 21Vrms(high amp voltage, ultra high gain, 600Ω load)
Headphone matching impedance
8Ω - 600Ω
ES9038PRO x 1
Volume control
Reference clock jitter
0.038 picoseconds (38 femtoseconds)
Charging port
Available Type-C port, DC port available, QC2.0 quick charge.
External power supply
DC 5.5*2.1 port, can also be charged (panel switch selection)
Battery Life
8 ~ 9 hours (depending on settings, music format, load condition)
Charging time
Type-C common charge: 8 ~ 9 hours, Type-C fast charge / DC port: 4 ~ 5 hours
Product weight
Product Size
20cm x 18cm x 4.45cm
Output parameters
1900mW / ch
360mW / ch
180mW / ch
High amp voltage and high gain
High amp voltage and supper high gain
High amp voltage and supper high gain
Balance headphone port rated output power
2800mW / ch
1200mW / ch
720mW / ch
Medium amp voltage and supper high gain
High amp voltage and supper high gain
High amp voltage and supper high gain

Audio Formats

Local play (SD card) Audio Bit depth, Sample Rate  Container, Encoding, Compression
WAV  64Bit / 192KHz, 24Bit / 352.8KHz  Fixed-point, Floating-point
AIFF  24Bit / 352.8KHz  
FLAC  24Bit / 352.8KHz  Level 0~8
ALAC  24Bit / 48KHz  M4A Container
WavPack  24Bit / 48KHz  Fast / Normal / High / High Plus
APE  C1000: 24Bit / 192KHz
 C2000: 24Bit / 192KHz
 C3000: 24Bit / 192KHz
 C4000: 24Bit / 96KHz
 Fast / Normal / High / Extra High
TTA  24Bit / 48KHz  
DIFF  DSD64 - DSD128  Not support DST encoding
DSF  DSD64 - DSD128
MP3  16Bit / 48KHz, 96-320kbps  CBR / VBR / ABR encoding
AAC  16Bit / 44.1KHz  M4A Container, AAC LC / SBR encoding
DTS  16Bit / 44.1KHz  WAV Container, DTS-5.1/DTS-ES
CUE  ANSI / Unicode / Unicode Big-endian / UTF-8 encoding
USB-PC  PCM 32Bit / 384KHz, DSD256
USB-Phone  PCM 32Bit / 384KHz, DSD128
Blue-tooth  Supports Bluetooth 5.0, Supports HD Bluetooth up to 24Bit / 96KHz
Coaxial / optical input  PCM 24Bit / 192KHz, DSD64 (DoP)
Coaxial / optical output  PCM 24Bit / 192KHz, DSD64 (DoP)

Front Panel


 Function instruction

A  Power switch
B  DC IN charging selector switch
C  Off-screen indicator (this light is on when the screen is off)
D  Charging status indicate lamp
E  Infrared remote receive window
F  XLR balance output port
G  Volume knob (can control the headphone output and PRE-AMP function volume)
H  Balance headphone output port (suitable to 2.5/3.5/4.4 insert needle)
I  Single end headphone output port (suitable to 3.5/6.35 insert needle)

Back Panel


 Function instruction

A  XLR balanced output right channel
B  XLR balanced output left channel
C  RCA output right channel
D  RCA output left channel
E  RCA coaxial digital output
F  RCA coaxial digital input
G  Optical digital output
H  Optical digital input
I  USB input - connect the phone (no camera kit required)
J  USB input - connect to the computer
K  Type-C charging input (support fast charging)
L  Power input (Power supply & Fast charge)

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