Overview

The LONG ZHONG DUI (隆中对), named after the celebrated strategic counsel of the Three Kingdoms era, is a USB Type-C to 3.5mm DAC adapter from Harmonic Empire, a sub-brand of Tangzu Audio. Built around the KTMicro KT02F20 DAC chip, it supports PCM audio up to 24-bit/192kHz (claimed) and operates as a plug-and-play device requiring no driver installation on Android, iOS (USB-C), Windows, and macOS. The official price is 9.90 USD on the Tangzu website [1]. The product is distinguished primarily by gradient anodized metal housing and Three Kingdoms thematic branding in a compact 120mm non-detachable cable form factor.

Scientific Validity

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Manufacturer specifications state THD+N of 0.01%, S/N ratio of 105 dB, dynamic range of 98 dB, and a frequency response range of 20Hz–20kHz [1]. The THD+N and S/N ratio figures sit at the boundary between adequate and high-performance territory for a portable DAC; the dynamic range of 98 dB is a moderately capable figure but falls short of high-performance levels. An unresolved discrepancy exists in the claimed maximum sample rate: the manufacturer states 192kHz, while the KTMicro KT02F20 chip manufacturer’s specification lists a maximum of 96kHz for this part [4].

No independent third-party measurements are available for this product from any credible measurement laboratory. Because evaluation relies entirely on manufacturer-provided specifications, actual on-device performance may differ from these figures.

Technology Level

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The Long Zhong Dui uses the KTMicro KT02F20, a commercially available off-the-shelf chip also used identically in competing products including the TRN TE and QKZ TC MAX. No in-house chip design, proprietary circuit topology, or technical patents are present. The product is a cosmetically differentiated reference design with no unique audio engineering contribution. The manufacturer’s claim that silver-plated copper cabling provides improved signal stability has no scientific basis at this cable length and form factor. Any manufacturer can source the same chip directly, and the product offers no lasting competitive advantage.

Cost-Performance

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The Long Zhong Dui is priced at 9.90 USD [1]. Note that the official Tangzu listing was sold out at the time of this review; availability may vary by retailer. Among products providing equivalent or better user-facing functions — USB-C input, 3.5mm single-ended output, plug-and-play compatibility, and equivalent or better audio performance — the Jcally JA04 at 8.99 USD [2] is the cheapest confirmed alternative currently available in the US market.

The JA04 provides all functions of the review target and additionally includes microphone passthrough. Manufacturer-specified performance is superior on all measurable axes: THD+N 0.003% vs 0.01% (JA04 better), S/N ratio 125 dB vs 105 dB (JA04 better), dynamic range greater than 100 dB vs 98 dB (JA04 better), frequency response 20Hz–20kHz (equivalent), and PCM support up to 384kHz vs the claimed 192kHz (JA04 better). This comparison is provisional, as neither product has independent third-party measurement data; results may be revised when such data becomes available.

CP = 8.99 USD ÷ 9.90 USD = 0.9081 → 0.9

Reliability & Support

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The Long Zhong Dui carries a 1-year manufacturer warranty for manufacturing defects [3], below the two-year industry average. The device’s construction is inherently simple and robust — a metal-bodied dongle with an integrated DAC chip, no moving parts, no battery, and no wear-prone components — which supports physical longevity. No firmware or software updates are applicable, as the device operates as a standard USB Audio Class 2.0 device requiring no proprietary software. Support is distributed through regional authorized dealers in India, Indonesia, and Hong Kong, with no centralized manufacturer support infrastructure. No documented hardware failures or reliability issues have been identified.

Rationality of Design Philosophy

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The Long Zhong Dui correctly uses a solid-state digital implementation and fulfills a clear functional purpose as a headphone adapter for USB-C devices. However, the product’s investment is primarily directed at brand identity and aesthetics rather than audio engineering: gradient anodizing and Three Kingdoms/anime branding represent the principal points of differentiation, contributing nothing to audio performance. The manufacturer’s claim that silver-plated copper cabling provides “stable signal transmission” constitutes an audibility claim for a materially non-contributing element without scientific support. The product applies a cosmetic layer to a commodity reference design shared with multiple competitors, with no technical differentiation in the audio domain.

Advice

The Long Zhong Dui functions adequately as a USB-C to 3.5mm adapter at its official 9.90 USD price. However, the Jcally JA04 at 8.99 USD offers superior manufacturer-specified performance across all measurable axes — SNR of 125 dB vs 105 dB, THD+N of 0.003% vs 0.01%, dynamic range exceeding 100 dB vs 98 dB, broader PCM support (384kHz vs 192kHz), and microphone passthrough — at a lower price. Both products lack independent third-party measurement data, so the relative performance picture may shift once such data is available.

Buyers primarily motivated by the Three Kingdoms aesthetic and Harmonic Empire brand identity will find the Long Zhong Dui a functional device with no apparent hardware reliability concerns. Those prioritizing the best documented audio specifications per dollar should consider the Jcally JA04 as the stronger technical choice at approximately the same price.

References

[1] TANGZU - HE Longzhong 3.5mm Single-Ended Interface Adapter - https://tangzu.net/products/he-longzhong-3-5mm-single-ended-interface-adapter - Accessed 2026-05-27

[2] HiFiGo - JCALLY JA04 Adapter ALC5686 - https://hifigo.com/products/jcally-ja04 - Accessed 2026-05-27

[3] Headphone Zone - Harmonic Empire Long Zhong Dui 3.5mm to Type-C DAC - https://www.headphonezone.in/products/harmonic-empire-longzhong - Accessed 2026-05-27

[4] KTMicro - USB Audio Series (KT0200 Series) - https://www.ktmicro.com/?usb_73%2F175.html= - Accessed 2026-05-27

(2026.5.28)