Overview

The KZ ZAX is a 7BA+1DD hybrid earphone developed by China’s Knowledge Zenith. It features a 10mm dynamic driver and seven balanced armatures (30019×2, 50024×4, 30095×1), with an impedance of 24Ω and sensitivity of 113dB/mW. The housing design combines zinc alloy and acrylic resin, and a silver-plated cable is included. Positioned as the company’s flagship model, it was developed aiming for a more balanced sound quality than previous KZ products.

Scientific Validity

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According to measurement data from Reference Audio Analyzer, non-uniformity in frequency response has been confirmed, with deviations observed in the 20Hz-20kHz range. However, due to differences in measurement environments and conditions, verification by multiple measurement sources is desirable. Regarding THD (Total Harmonic Distortion), detailed measurement data has not been published, but for the headphone/earphone category, 0.05% or below is considered an excellent level, while 0.5% or above becomes a problematic level. Specific values for the S/N ratio also cannot be confirmed, raising questions about whether it meets the transparent level of 105dB or above. Compared to the transparent levels achieved by current high-performance DACs and amplifiers in the measurement results reference table, the audible sound quality improvement effects are limited.

Technology Level

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The 7BA+1DD hybrid configuration is a technically interesting attempt, but it represents an industry-standard level of design. The combination of a 10mm dynamic driver and multiple BA units is commonly adopted by other companies as well, showing no particular uniqueness. Detailed technical information about the crossover design has not been published, giving a strong impression of simply increasing the number of drivers. While the machining precision of the zinc alloy housing is good, no technical advantages that directly contribute to innovation in acoustic design or improvement in measured performance can be confirmed. By current latest technology standards, it remains at the level of combining existing technologies.

Cost-Performance

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The current market price of the KZ ZAX is approximately 40 USD, but a competing product with equivalent or superior performance exists: the Moondrop Chu II (approximately 20 USD). The Moondrop Chu II has a flatter frequency response and is significantly cheaper, despite being a single dynamic driver configuration. Cost-performance is calculated as “price of competitor ÷ price of product under review,” so “20 USD ÷ 40 USD = 0.5,” resulting in a score of 0.5. Furthermore, the quality of the included cable and eartips is low, requiring additional accessory investment to reach a practical level, which means its price competitiveness in the market cannot be considered high.

Reliability & Support

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KZ is an emerging Chinese audio manufacturer, and limited information is available regarding its quality control systems and long-term reliability. The warranty period is a standard one year, but repair support systems are not well-established in many regions outside of China. Specific reliability data such as RMA (Return Merchandise Authorization) ratios and MTBF (Mean Time Between Failures) have not been published. Online reviews show scattered reports of sound quality variations due to individual differences and durability concerns with the cable connection parts. Since firmware updates are not necessary, evaluation on this point is not applicable. The support system is estimated to be at an industry-average level, but this has not been confirmed.

Rationality of Design Philosophy

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The design philosophy of aiming for wide-range reproduction through a multi-driver configuration is understandable, but judging from the measurement results, simply increasing the number of drivers does not directly lead to sound quality improvement. The resonance peak around 8kHz suggests design problems, and the crossover design appears to be insufficiently optimized. With current technology standards, it is possible to achieve a flatter frequency response with fewer drivers, and the negative effects of complexity may be greater. While the attitude toward price disruption is commendable, there is a strong impression of a design that prioritizes marketing appeal over measurement performance improvement. Non-rational aspects can be seen that prioritize visual impact over scientifically-based sound quality improvement.

Advice

For those considering purchasing the KZ ZAX, I recommend alternatives that offer equivalent function and are superior. For those prioritizing measured performance, the Moondrop Chu II, with its flatter frequency response, is available for approximately 20 USD. If you choose the KZ ZAX, due to the low quality of the included accessories, I recommend additionally purchasing SpinFit eartips (approximately 10 USD) and a replacement cable (approximately 13 USD). For music genres, it is suitable for EDM and rock that emphasize bass impact, but not for applications requiring soundstage accuracy such as classical and jazz. In the current market environment, it is important to recognize that multiple scientifically superior choices exist within the same budget and to make an informed decision.

(2025.7.23)