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Hifiman HE400se

Planar Magnetic Headphones By Sam Inglis
Published September 2022

Hifiman HE400se

Hifiman’s mission to democratise premium headphone technology continues.

Back in April I looked at three models from Hifiman’s extensive range of studio and hi‑fi‑oriented headphones. Of these, the Arya and Sundara are notable for being planar magnetic designs. In the right hands, this technology can deliver impressive results, but relatively few manufacturers have mastered the art of making high‑quality planar magnetic drivers, and they tend to be quite pricey. So, at a shade under £300$350, the Sundaras are one of the most aggressively priced open‑backed planar models on the market, and they definitely punch above their weight. With that in mind, I was intrigued to try out another Hifiman planar model which is even more affordable.

The HE400se is similar in general design to the Sundara, but in typical Hifiman fashion, they differ in almost every detail, from the Y‑shaped cable to the pattern of the grille. The two models’ earcups are pretty much the same diameter, but those of the HE400se are noticeably deeper, and are finished in silver rather than black. They use a conventional padded headband rather than the two‑piece design of the Sundara, and accessories such as the cable and packaging have a rather more basic feel to them, quality‑wise. That’s hardly surprising given the cost of the HE400se, which retails at an astonishingly low price for a planar magnetic model. I found them adequately comfortable, though the headband is quite narrow and thus tends to bear down on one particular spot on top of the head.

Stealth & Efficiency

Hifiman models incorporate diverse proprietary technologies, including asymmetrical drivers and earcups, and the Window Shade louvre design employed on the Arya. Not to be left out, the HE400se boasts “stealth magnets” which are said to reduce “wave diffraction turbulence” and, consequently, lower distortion. With a nominal impedance of 32Ω they should be easy to drive from any source, and although they are 3dB less sensitive than the Sundara, I don’t think they will prove a challenging load for headphone amps. In general, in fact, the historic problem of low sensitivity now seems to have been thoroughly overcome in modern planar magnetic designs.

Even the more affordable planar models from manufacturers such as Audeze and Avantone cost several hundred, so the HE400ses are really sharing this sector of the market only with Fostex’s T20RP Mk3.

The other issue that has traditionally limited the performance of planar headphones is high‑frequency response. This is something Hifiman have worked very hard to address, and all the models of theirs I’ve tried have an impressively extended treble. The HE400se is no exception, and I can’t imagine anyone calling them dull or muted in tonality. However, at this price it perhaps isn’t surprising that they don’t sound perfectly neutral either. There’s a subtle but persistent sharpness somewhere in the 4kHz range that can make cymbals, tambourines and vocal sibilance stick out jarringly; and, if anything, there’s actually a slight dip in the low midrange. In a direct comparison with the Sundaras, I also had the feeling that the very low bass was quite subdued, which is a shame as this is generally a strength of planar magnetic designs.

With the possible exception of this anaemic low bass, though, any other non‑linearities in the frequency response of the HE400se should be easy enough to address using Sonarworks or similar corrective equalisation. If that’s the case, they present a pretty compelling value‑for‑money proposition. Even the more affordable planar models from rival manufacturers such as Audeze and Avantone cost several hundred, so the HE400ses are really sharing this sector of the market only with Fostex’s T20RP Mk3s, which sound very different. And whilst their low cost is to a certain extent apparent both in their build quality and their sound, they still represent an awful lot of headphone for the money.


The HE400se makes Hifiman’s planar magnetic technology available at a remarkably low price, without losing most of its core benefits.


£129 including VAT.