Overview

The HiFiMan HE400se is an entry-level open-back headphone from the company, featuring planar magnetic driver technology. Released in the 2020s, it is positioned at an affordable price point of approximately USD 109 and incorporates a proprietary magnetic circuit design called Stealth Magnets. By its nature as an open-back headphone, it is specialized for listening in quiet environments and is characterized by an open, spacious soundstage.

Scientific Validity

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The HiFiMan HE400se has a frequency response of 20Hz to 20kHz, a low impedance of 25Ω, and a claimed sensitivity of 91dB SPL. In actual measurements, the sensitivity is a relatively low 86.6 dB/mW, meaning it requires significant power to reach adequate volume levels. Regarding its THD characteristics, it achieves the low distortion inherent to planar magnetic drivers at this price point, showing an advantage especially in low-frequency distortion compared to many dynamic driver headphones in the same price range. Channel matching is good, but there is a characteristic dip in the 1-3kHz band typical of HiFiMan products.

Technology Level

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It adopts a magnetic circuit design called Stealth Magnets that reduces acoustic interference. The 80mm diameter planar magnetic driver uses technology inherited from the company’s higher-end models, but it is fundamentally an entry-level design. The impedance characteristic is almost purely resistive at 26.5Ω, with minimal phase shift. However, compared to higher-end models like the Sony MDR-MV1 at approximately USD 400 or the TAGO STUDIO T3-01 at approximately USD 550, there are clear differences in driver accuracy and housing design sophistication.

Cost-Performance

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The HiFiMan HE400se is priced at approximately USD 109 (as of August 2025, on Amazon.com). Based on the function this product provides—an “open-back listening experience”—and its measured performance, there are virtually no cheaper alternatives within the product group that offers the same function. Regardless of driver technology, when evaluated on a pure performance-to-price basis within its functional category, the cost-performance score is a perfect 1.0.

Reliability & Support

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It comes with a 1-year warranty from HiFiMan and is sold through official channels. The company has a solid track record as a veteran manufacturer of planar magnetic headphones, but its support system and repair services are at industry-standard levels. Public information about product failure rates is limited, but it can be assessed as having typical reliability for an entry-level product. As a wired headphone, firmware updates are not applicable.

Rationality of Design Philosophy

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The low 25Ω impedance design seems intended for use with portable devices. However, this is paired with a very low measured sensitivity of 86.6 dB/mW, which results in most smartphones and portable players being unable to provide sufficient driving power to unlock its performance. This combination of specifications, where it is designed for portability but requires a stationary amplifier in practice, represents a divergence between design philosophy and actual performance, thus its rationality cannot be rated highly.

Advice

The two most critical factors in considering these headphones are your listening environment and whether you have a dedicated headphone amplifier. As an “open-back” model, it, by design, leaks a significant amount of sound outwards and provides almost no isolation from ambient noise. This makes it entirely unsuitable for use in any environment where quiet operation or noise isolation is needed, such as on public transport, in a café, or in an office.

Furthermore, when connected directly to a smartphone or PC, its low sensitivity makes it difficult to achieve adequate volume and clean, undistorted sound quality. To experience the superb acoustic capabilities of this headphone, a dedicated headphone amplifier is effectively a requirement.

If your use is confined to a quiet space at home and you can provide proper amplification, then the HiFiMan HE400se is one of the strongest contenders in its price range. Under these specific conditions, it is difficult to find a product with superior measured performance for less money, regardless of driver type.

Additional Information

This product claims a sensitivity of 91dB SPL, but actual measurements show 86.6 dB/mW. It is important to note this discrepancy. This low sensitivity is the primary reason a headphone amplifier is necessary to achieve sufficient volume. Also, the characteristic dip in the 1-3kHz band is common to many HiFiMan products, and personal preference for this acoustic signature will be an important factor in product selection.

Review Date

(2025.8.1)