One of the most important features of the HE400se is its planar magnetic driver technology. In traditional dynamic headphones, the diaphragm (1.) is driven only at specific points, while in a planar design the conductive layer (2.) is distributed across the entire surface of the diaphragm. The magnetic (3.) force moves the entire diaphragm evenly, resulting in more controlled movement with lower distortion.

Thanks to this operating principle, the rendering of fine details improves, instrument separation becomes more precise, and a more natural sense of space is created. The lower moving mass is especially beneficial for reproducing high frequencies, while the even diaphragm control contributes to a balanced sound across the entire frequency range.

The HE400se uses HiFiMAN’s Stealth Magnet design, which aims to minimize the acoustic impact of the magnets. The specially shaped magnets interfere less with the sound waves produced by the diaphragm, reducing distortion caused by diffraction and turbulence.

This solution allows sound waves to encounter fewer obstacles within the driver structure, contributing to a cleaner sound and a more natural rendering of detail. The technology shows its advantages especially in recordings where preserving subtle dynamic nuances and accurate spatial information is important.

The open-back construction allows both sides of the diaphragm to move more freely, contributing to a more airy sound and a wider sense of soundstage. The dual-sided cable with separate grounding reduces crosstalk between channels, supporting accurate stereo imaging.

As a result, the HE400se conveys the placement of instruments and the spatial information in recordings effectively. At the same time, due to its nature, the open-back design provides less isolation from external noise, so it is primarily intended for use at home in a quiet environment.

When developing the HE400se, HiFiMAN placed strong emphasis on wearing comfort. The headphones weigh approximately 30% less than comparable planar magnetic models, reducing strain during extended use.

The new adjustable headband and angled hybrid ear pads distribute weight more evenly while ensuring a proper fit. The drivers are protected by a newly designed outer housing, which increases mechanical durability and contributes to a long service life.

The HE400se uses a detachable cable with dual-sided 3.5 mm connectors, providing a stable connection between the headphones and the playback device. The screw-on locking mechanism helps prevent accidental disconnection while providing a reliable connection over the long term.

Thanks to the included 6.35 mm adapter, the headphones can be easily connected to desktop headphone amplifiers, DACs, Hi-Fi systems and other audio devices, while the 3.5 mm connection is also compatible with portable players and many other devices.

Due to its open-back planar construction, the HE400se has an airy, detailed sound that is easy to follow spatially. It is not built around excessive bass or an emphasized character, but around keeping instrument separation, layer transparency and the stereo image natural. As a result, the presentation feels clean and well organized, especially with acoustic music, vocal recordings and material where preserving fine detail is important.

The fast diaphragm movement of the planar magnetic driver and the even surface control help achieve lower distortion, which is essential for microdetail and positioning. The bass is more controlled than strongly emphasized, the midrange remains clearly traceable, and the treble, together with the open-back construction, delivers a more spacious, airy presence. Overall, the HE400se can be described as having a more neutral planar sound with a slightly bright tendency.