Overview

The QU02 converts USB to I2S (HDMI LVDS), AES/EBU, dual coaxial, and optical. It implements galvanic isolation on the USB side, an Amanero USB interface, dual Accusilicon AS338 oscillators, and DIP switches for I2S flag/polarity to maximize DAC compatibility[5]. Typical market price used for this review is 389.99 USD (non-sale list)[3].

Scientific Validity

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Comprehensive third-party jitter spectra for QU02 are not yet available, so we start from the 0.5 baseline when measurements are unknown. Manufacturer-published numbers indicate an AS338 clock (38fs jitter, -109.5dBc/Hz at 10Hz) and ~80ps coaxial output jitter; these show a low-jitter intent but remain provisional until independently verified[5]. Final audibility depends on DAC PLL/ASRC behavior; we refrain from stronger claims pending public lab data.

Technology Level

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Sound engineering choices—USB galvanic isolation, careful power partitioning with quality regulators, CPLD divider, and configurable I2S mapping—are aligned with current best practices[5]. With limited evidence of proprietary inventions or patents, we score slightly above average at 0.6.

Cost-Performance

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Result: CP = 1.0. Among DDCs offering all the same outputs (I2S/AES/coax/optical) and having independent jitter measurements, the cheapest credible option is Singxer SU-2 (GoldenSound measurements), typically 469-470 USD new[1][2][6]. The QU02’s representative price is 389.99 USD (non-sale)[3]. We found no cheaper equal-or-better alternative, so QU02 is the least-cost option meeting equivalence, yielding the capped score of 1.0. As context, Matrix X-SPDIF 3 sits higher at 499 USD[7].

Reliability & Support

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No broad RMA/MTBF datasets were found. Major retailer listing shows a two-year warranty for the product line[4]. With a simple, no-moving-parts design and no required firmware cadence, we keep an average 0.5.

Rationality of Design Philosophy

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The design targets plausible mechanisms—USB isolation, clean local supplies, and low phase-noise clocks—to suppress source-borne interference and interface jitter, while avoiding non-scientific claims[5]. The feature set (multi-standard outputs, configurable I2S) justifies a dedicated box for users who need these interfaces.

Advice

Best suited for DACs with I2S/AES inputs and systems seeking galvanic isolation from a noisy host. Verify your DAC’s I2S pinout and use the DIP switches accordingly[5]. If your DAC’s native USB input is already state-of-the-art, audible changes may be small. Price context: rivals with public lab data (SU-2/Matrix X-SPDIF 3) cost more[1][2][6][7].

Important caution: This device mainly makes sense when you need multiple digital outputs or when your DAC/system suffers from USB power/ground noise issues on the host side. Simply inserting a DDC before a competent modern DAC should not be expected to improve sound quality. Most recent USB DACs use asynchronous USB with robust jitter rejection and isolation, pushing USB-borne artifacts below audibility. If your goal is sound quality per dollar, a recent, well-measuring USB DAC at the same or lower total cost often provides the better outcome.

References

[1] GoldenSound, “Singxer SU-6 Measurements”, 2021-08-01, https://goldensound.audio/2021/08/01/singxer-su6-measurements/
[2] GoldenSound, “Singxer SU-2 KTE Measurements”, 2021-09-27, https://goldensound.audio/2021/09/27/singxer-su2-measurements/
[3] HiFiGo, “QULOOS QLS QU02 USB Digital Audio Interface”, accessed 2025-08-25, https://hifigo.com/products/quloos-qu02
[4] ShenzhenAudio, “QULOOS QU02 USB Interface” (two-year warranty shown), accessed 2025-08-25, https://shenzhenaudio.com/products/quloos-qu02-usb-digital-audio-interface-to-spdif-aes-ebu-i2s-supporting-dsd512
[5] Audiophonics, “Quloos QU02 — Accusilicon AS338, isolation, specs”, accessed 2025-08-25, https://www.audiophonics.fr/en/digital-interfaces/quloos-qu02-digital-interface-usb-to-spdif-i2s-accusilicon-as338-black-p-17112.html
[6] Kitsune HiFi, “Singxer SU-2 — Price”, accessed 2025-08-25, https://kitsunehifi.com/products/singxer-su-2-dsd1024-usb-digital-interface-femto-second-clock-interface-pcm-768k-hdmi-i2s-ddc-arm-processor
[7] Apos Audio, “Matrix X-SPDIF 3 — Price”, accessed 2025-08-25, https://apos.audio/products/matrix-x-spdif-3-usb-interface

(2025.8.25)