Hifiman HE400SE 2021 Stealth Version Review Open Back Planar Headphones

Monday, May 24, 2021

You don't have to be a so-called "audiophile" to care about the quality of your audio or to be in pursuit of sound clarity! Planar headphones have been the gold standard for many audio enthusiasts for quite sometime now and, thanks to budget-friendly offerings such as the Hifiman HE400SE, more people have the chance to jump on the planar bandwagon and enjoy the listening experience, which includes lots of detail on the high end.
The HE400SE stealth magnets version is the successor to the HE400S planar headphone model, which looks virtually identical. Same design aesthetics and donut style earpads, which have a perfectly round outer (10cm diameter) and inner hole (5.5cm diameter). The earpads are covered with protein leather and lined with a small trim of velour fabric (2cm wide) on the front of the earpad. The HE400SE earpads are comfortable and, while not as breathable as the HE400S, they don't get too sweaty, thanks to the hole perforation around the inner hole. The depth to the driver is 2.5cm so, the HE400SE earcups have slightly more room (0.5cm) to accommodate larger ears.

The HE400SE headband measures 3.5cm wide and has a hollow plastic construction frame padded throughout. The bottom section has 1cm thick foam padding and, it's a lot more firmer than the earcups foam padding (2.5cm thick), which is soft and squishy. The headphone yoke is designed to retract inside the headband frame and adjust via a ratchet style slider mechanism similar to the one in the Sundara headphones. The ratchet mechanism has eight tiny punch holes that allows incremental and secure height adjustment for the head. Being ratchet, the adjusting slider makes a bit of noise.

The front of the HE400SE earcups have a 10cm diameter and integrate an 8cm diameter plastic grille mesh. The total thickness of the earcups (including the ear pads), it's 5.5cm; hence HE400SE have a bulky design similar to gaming headphones. Below each earcup, you find a 3.5cm audio port plug inside a recessed cutout. While the HE400SE is virtually identical to the HE400S, the HE400SE (pictured) houses "stealth magnets", which produce a different sound signature. Because of the extra hardware, the HE400SE weigh 390 grams, which is heavier than the HE400S version (350 grams) and the HE400i (370 grams) version, which according to reports will be discontinued.

The HE400SE plastic earcup housing is attached to the metal yoke and held together via a slot head screw on either side. The slot screws also double as tilt adjustment pivots that allow the HE400SE earcups to rotate clockwise and anticlockwise around the yoke 360 degrees. There is no swivel mechanism so, the earcups cannot be twisted around to position them flat on a desk. That said, the headband yoke has a bit of play, which allows you to wiggle the headband yoke slightly.

As far as accessories, the Hifiman includes a 6.5mm jack adapter and a dual sided cable (1.5 meters long). Construction-wise, the HE400SE stock cable isn't as premium as the older HE400S cable, which is a thick fabric cable with a y-splitter. The HE400SE cable doesn't have a y-splitter and has a braided string design similar to the litz cable you get with a lot of budget IEMs. 
The cable has silver copper wiring wrapped around a thin clear sleeve, which is stiff and prone to microphonics. Being a litz cable, it's extremely lightweight (just 24 grams) and, it's perhaps the reason why Hifiman chose this type of cable, over a fabric cable, to cut down the weight since the HE400SE headphone is already heavier than its predecessors - HE400S and HE400i. The split section of cable that separates the right and left channel measures 46cm long. 

The included cable may not do the most justice to the HE400SE but, you can easily upgrade it. On the plus side, the HE400SE earcups use 3.5mm audio plugs, while the HE400S and HE400i versions use 2.5mm audio plugs. Compared to the HE400i and HE400S headphones, the HE400SE stealth drivers produce a more notable V-shaped sound signature. 

This means, the vocals fall behind the bass and treble, which are both elevated but neutralized so, the sound is flat sounding. Being open back, the sound naturally leaks out of the earcups, which in turn eliminates echos, making the sound very spacious, and not confined like a closed-back headphone. The HE400SE have particularly amazing soundstage - more height, width and depth than the HE400S. Being planar, the sound can be easily customizable via an equalizer.

The HE400SE have low impedance (25 ohms) and high sensitivity (91dB), which allows you to drive them from a smartphone. The volume output is slightly lower on the HE400SE than on the HE400S (22 ohms - 98dB), HE400i (35 ohms - 93dB) and Deva (18 ohms - 100dB). If you click on those links, you can listen to the volume tests and hear for yourself. Like with most planar headphones though, you ideally want to use external amplification if you want more volume out of the headphones.

The HE400SE planar headphones come packaged inside a plastic inner holder and a hardback outer box. It's also worth pointing out the Hifiman sells two versions of the HE400SE - the Chinese edition and the global edition (pictured), which is the "stealth magnet" version. You can buy the HE400SE planar headphone directly from Hifiman. Check out the review of the Hifiman Deva planar headphones. 

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