Overview

The Sennheiser HD-600 is an open-back dynamic headphone released in 1997 that has been used as a reference in the professional audio industry for many years. It features a high impedance design of 300Ω and frequency response of 16Hz-30kHz. The design philosophy with over 20 years of history was groundbreaking at the time, but from current technical standards, some aspects require updates. While it still receives recognition in the industry, the relative positioning has changed due to the rise of emerging manufacturers.

Scientific Validity

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The HD-600’s measured performance includes 300Ω impedance, 0.1% THD, and 16Hz-30kHz (±1dB) frequency response. AudioScienceReview (ASR) measured sensitivity at 103.7dB/V, while Stereophile reported 97dB SPL (equivalent to approximately 102dB/V). The difference likely stems from Sennheiser’s specification mixing dB/mW and dB/V units. Both measurements confirm generally flat frequency response in the critical 30Hz-20kHz range with acceptable THD levels for transparency. As a dynamic driver design, it exhibits inherent physical constraints compared to planar magnetic drivers in transient response characteristics.

Technology Level

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The HD-600 is a 1997 design featuring excellent 300Ω dynamic driver engineering for its era. However, current standards reveal technical obsolescence compared to modern planar magnetic drivers and latest amplifier technologies. Planar magnetic drivers like the HiFiMan HE400se demonstrate advantages in distortion characteristics and transient response through their fundamentally different driver architecture. While Sennheiser’s engineering approach remains technically sound, it represents established rather than cutting-edge technology. The design has achieved high completion but shows limited innovation over its 28-year production run.

Cost-Performance

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The HD-600’s current market price is 315 USD (Amazon July 2025). As an equivalent open-back headphone, the HiFiMan HE400se is available for 130 USD. The HE400se features 91dB SPL sensitivity, 25Ω impedance, and planar magnetic drivers, but despite its low impedance, requires approximately 1000mW for optimal performance due to its planar magnetic design. Calculation: 130 USD ÷ 315 USD = 0.413, rounded to 0.4. Both products require amplifiers with substantial driving capability, with HD-600 needing high voltage for its 300Ω impedance and HE400se requiring high current for its power-hungry planar drivers.

Reliability & Support

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Sennheiser maintains certain reliability as an established audio manufacturer. The HD-600 has over 20 years of sales history, and the continued product and parts supply over the long term is commendable. However, the company sold its consumer business to Swiss company Sonova in 2021, and future support structure is planned to continue under Sonova. While repair services continue, new technology adoption and firmware updates cannot be expected. The warranty period is at industry standard level and is not particularly outstanding.

Rationality of Design Philosophy

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The HD-600’s 300Ω high impedance design requires a dedicated amplifier, reflecting 1990s professional audio optimization. The HE400se, despite its 25Ω impedance, actually demands approximately 1000mW due to planar magnetic driver characteristics, resulting in both products requiring substantial amplification. The HD-600’s unchanged design over 28 years demonstrates either perfected engineering or technological stagnation. While conservative, the approach prioritizes proven performance over modern innovations like efficient driving solutions or advanced materials. The open-back acoustic design remains fundamentally sound.

Advice

The HD-600 is an excellent headphone with a long history, but we do not recommend it at the current price of 315 USD. For the same budget, the combination of HiFiMan HE400se (130 USD) and a high-quality amplifier would be a more rational choice. The HE400se requires substantial power (approximately 1000mW) despite its low impedance, so dedicated amplification remains essential for both options. While both products have similar amplification constraints, the significant price difference makes the HE400se clearly advantageous. The HD-600 retains value through its professional audio heritage and proven reliability, but for pure cost-performance, equivalent planar magnetic alternatives exist at substantially lower prices.

(2025.7.20)