Review: SJY Zeph Open-Back Planar Magnetic Headphones

How much of a difference can the earpads on a set of headphones really make? The idea of getting a noticeable sonic difference based on the size and shape of thin pieces of foam under leather or velour sounds like audiophile snake oil.

As a fan of vintage electrostatic headphones, I’ve confidently operated under this belief by chintzing out and buying replacement earpads of roughly the right size and shape rather than ponying up $100 or more for OEM. It never occurred to me that this might have been a mistake until I tested SJY’s new Zeph open-backed planar magnetic headphones.

The end result is far from a gimmick—they’re among my favorite pair of headphones of all the ones I’ve ever used.

Magnetic Sound

Photograph: Martin Cizmar

Most consumer headphones and speakers reproduce sound by vibrating a cone using a wire coil. But the Zeph is different. It’s a planar magnetic headphone, which means it uses a magnetic field to vibrate a flat, thin diaphragm to reproduce sound. These have a faster and more accurate sound but are generally thought to sacrifice some punch on lower bass frequencies. Planar magnetics are a growing category that is expected to more than double in the next decade—even if these headphones remain niche today.

I’ve owned a few pairs of planar magnetics and am generally a fan because I like loads of detail in my music. True to form, the Zeph has exceptional detail and frequently delivers the hyper-real quality I look for in headphones of this range. It aced my favorite reference test, which is being able to hear Keith Moon move around on a squeaky stool during the opening of “Won't Get Fooled Again.” On Radiohead’s “Daydreaming” from A Moon Shaped Pool, the glockenspiel pierces through the piano and loops with a shimmery quality. Listen closely, and you can hear the metronome in the left channel (and that’s all with the less-detailed holes-in-front orientation). The precision and texture here is unprecedented. Meanwhile, there is plenty of low-end for my taste—I get a thick, bouncy bass when clicking forward to “Identikit.”

Note, though, that planar magnetic headphones generally require more amplification than standard headphones, and the Zeph is relatively power-hungry. It will demand at least a watt per channel, or preferably more. I have a handful of headphone amps and DAC dongles lying around, but only one device that can drive the Zephs. That’s a Creative Soundblaster X5 that has a balanced 4.4-mm headphone port. The 4.4-mm port is pretty standard on audiophile equipment these days, but it’s worth a warning to regular folks who are accustomed to standard 3.5-mm and 6.3-mm headphone jacks. You won’t be able to buy these headphones and plug them into even a standard stereo receiver.

Thin Mint

Photograph: Martin Cizmar

The Zeph’s magnetic earpads are flippable, with one side having pinprick-thick microperforations and the other being smooth. You can tweak the sonic signature by swapping the seam from down to up. If the size with holes is in front of your ear, the tuning becomes slightly colder and wider, with added pop to instruments. Flip the pads over so that the millimeter-thick holes are behind your ear and the sound signature is a tad warmer and more cohesive, with mixes sounding more blended.

The disparity is relatively subtle—like the difference between a martini that’s stirred (holes in front) as opposed to shaken (holes in the back)—but it’s definitely audible. I tend to prefer headphones with an expansive soundstage and lots of detail. Though with the SJY, I find the slightly warmer and more natural sound more inviting for long listening sessions. And these are headphones that can live comfortably on your head for long stretches.

The impact of the simple switch of earpad orientation is made possible partly because of the design’s arch minimalism. The design was intended to have as few pieces as possible and to hold them rigidly in place with the goal of achieving purity of sound. The aluminum chassis, diaphragm, and driver all measure low, single-digit millimeters. The entire body that clips onto the pads combined is only as thick as a typical monthly magazine in 2026.

Photograph: Martin Cizmar

Because of that, these headphones feel more like a carbon steel pocketknife in the hand than a pair of ANC Bluetooth headphones. They have an impressive sturdiness and don’t feel like something you’ll worry about breaking if you fall asleep with them on. They do weigh more than a pound—at 570 grams with their cable, they’re almost 40 percent heavier than AirPods Max. They come with a padded case that has a generous layer of foam for protection and a braided cable.

Despite their relative heft, I’ve had them perched on my head very consistently since the testers arrived. That’s mainly due to the detailed sound they render from the many gigs of too rarely used 24-bit Hi-Res FLACs on my desktop, as headphones like this can make old songs sound new again. And if it starts to sound old again? Just flip those earpads to have the holes on the other side, and it’s a whole new ballgame.

Curve Killers

The flippable earpads are also made possible by the way they’ve been tuned. High-end wired headphones are having a bit of a renaissance, growing slowly while the rest of the audiophile market dies off around them. But they are also getting more homogenized. That’s because the major makers are aiming to tune their products along the Harman Curve, a guideline for the ideal earphone frequency response built from extensive scientific research, including blind listening.

While the Harman Curve is controversial among enthusiasts on message boards, it’s been widely adopted by headphone makers who strive to get their stock tuning on target. SJY doesn’t reject the Harman Curve but has tweaked the tuning away from it and, even more interestingly, intentionally allows a listener to switch up the signature depending on the orientation of the earpads. That’s what makes them so unique in a world saturated with headphone options. After all, SJY is first and foremost an enthusiast brand, owned and operated by Jeffrey Yin, who started the company in 2020 on the day after his 18th birthday. The SJY line has four models so far, with a fifth on the way, all made by Yin himself in Houston. You don’t buy these to have just another pair of headphones. We hope that’s obvious enough.

But for me, it’s as close to a perfect pair of headphones as I’ve ever owned.

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