QLS QU02: High-quality USB – SPDIF and I2S digital interface

QU02 from Quloos is a high-quality USB – SPDIF and I2S digital interface that uses only high-end components to ensure the most transparent and accurate audio reproduction possible. It can also be used as an external sound card to enhance the sound quality of a DAC or audio player.


The QU02’s power stage is divided into several isolated segments, each of which is responsible for providing clean and efficient power to the various interface circuits while minimizing interference that could alter the signal. This power stage also includes multiple LT3042, LT1963, and LT3693 voltage regulators that provide excellent noise and transient performance. It also uses Philips 135, Philips 030, Murata, WIMA, ERO and Panasonic SMD capacitors to ensure effective filtration and isolation.

Often USB interfaces are used with 5V power from the USB input, so the sound is inevitably affected by the quality of the USB input power. Since the QU02 uses a Murata power supply isolation module and rejects the 5V power supply from the USB input, the interface is completely free from the influence of this power supply mode. The result is improved sound quality regardless of the source, and reduced differences in playback between two different sources.

Lower jitter results in improved audio quality and greatly improves consistency in the mid and low frequencies to which the human ear is more sensitive. High frequencies are also improved, becoming more delicate and precise. Thus, Quloos QU02 uses a high-precision clock from Würth Teknology for its processor to significantly limit electromagnetic interference. This clock’s stability and low jitter provide better placement of the sound image for an enhanced sense of immersion.

The QU02’s audio circuitry uses two high-end Accusilicon AS338 oscillators to deliver superior jitter and phase noise performance. Indeed, the jitter of this model is only 38 fs, and the phase noise at a frequency of 10 Hz is -109.5 dBc/Hz.

Both ends of the QU02 isolation are powered by a local power supply, providing an extremely clean and stable electrical signal, resulting in clearer and more detailed sound. In the QU02, the data processing unit (CPU), output processing stage and clock are completely isolated. The purpose of this isolation is to eliminate interference from the signal source to achieve greater audio fidelity.

The Quloos QU02’s HDMI I2S output can be configured to four popular I2S sequences for maximum compatibility with different brands of DACs.


Characteristics of QLS QU02:

  • Product Type: USB Interface
  • Input: 1* USB-B
  • Outputs: 2* coaxial/1* optical Toslink/1* AES/EBU/1* I2S HDMI
  • Supported sampling rates: I2S: PCM up to 32bit 384kHz, Native DSD up to DSD512/AES: PCM up to 24bit 384kHz, DSD DoP up to DSD128/Optical: PCM up to 24bit 192kHz, DSD DoP up to DSD64/Coaxial: PCM up to 24bit 384 kHz, DSD DoP up to DSD128
  • Output Impedance: I2S: 100 ohms (LVDS) / AES: 110 ohms (3Vpp) / Coaxial: 75 ohms (0.55Vpp).
  • Clock: AccuSilicon AS338
  • Voltage stabilizers: LT3042/LT1963/LT3693
  • Supply voltage: DC 12V 2A via 5.5/2.1mm DC jack
  • Consumption: 5W
  • Dimensions: 197x197x45 mm
  • Weight: 1.29 kg
  • Black color