Thieaudio Cypher is an open-back dynamic driver headphone priced at $399 (and often seen closer to $329 via Kickstarter). Coming from a brand better known for IEMs, and after a lukewarm experience with their previous open-back headphone Wraith, this one had reason to be approached cautiously. Surprisingly, the Cypher ends up being one of those headphones that—despite some clear flaws—comes close to fitting nicely in the existing market... provided they can get some things ironed out. 

Build, Design, and Comfort

The Cypher leans into a lightweight design philosophy, featuring a carbon fiber headband and a suspension strap system. On paper, this is exactly what you want for long listening sessions, and in practice, it mostly delivers. Where things get a bit less ideal is in clamp force and pad design. The clamp is slightly on the tighter side—especially for larger heads—and the pads, while soft and compliant, compress enough that ears may touch the inner chamber that houses the baffle and driver. For some, that’s going to be a dealbreaker.

The pads attach magnetically, which is convenient, but also limits easy pad swapping unless alternatives use the same mounting system (which for a headphone like this, seems unlikely). Visually, the design is… a choice. Not my kind of thing, but I could see people vibing with this.

More concerning, however, is the cup swivel mechanism. While it holds position well (maybe even too well), the stiffness of the adjustment seemingly varies between sides, and there’s no natural centering behavior. That inconsistency raises some mild concerns about quality control.

Lastly, despite being labeled as open-back, the Cypher behaves more like a semi-open design. There’s some attenuation of outside noise, but not to the degree of a fully open headphone. This may have effects on the perception of the sound produced by the headphone, so now lets talk about sound.

Sound

The defining characteristic of the Cypher is its midrange. This is a clearly mid-forward headphone with a tuning that prioritizes vocal presence and tonal richness over excitement at the extremes. And to its credit, it kinda works—there really aren't any outright deal breakers when it comes to the overall tuning here.

The midrange is impressively detailed and textured for its mild warm tendency. There’s a spotlighting here that gives vocals and instruments a natural, engaging quality. It’s the kind of presentation that draws you in quickly. However, it does go a bit too far in the warm direction, so this emphasis on warmth and ease of listening does come at the expense of a bit of contrast and dynamism.

The treble is notably relaxed. There are no harsh peaks or aggressive resonances, so I think this is something that will likely appeal to treble-sensitive listeners. But that smoothness comes with yet another trade-off: The treble lacks bite and incisiveness, often coming across as slightly hazy or indistinct. 

The bass is well-behaved but underwhelming. It extends reasonably well and remains tight, but it doesn’t deliver much impact or physicality. For listeners who prefer a more neutral or bass-light presentation, this may be acceptable. For others, it will feel like something is missing.

This is an intimate-sounding headphone. If you’re familiar with the “in-your-head” presentation of the Sennheiser HD6 series, the Cypher follows a similar path. There’s limited sense of space or width here. If soundstage is a priority, this isn’t the headphone for you.

Unit Variation and Channel Imbalance

Unfortunately despite me overall feeling quite positive about the Cypher's sound, it has notable, audible channel imbalance. Measurements indicate that the left and right channels have a persistent 2dB difference through the midrange, which is the kind of imbalance that will be audible to most people and shouldn't be an issue for a headphone at this price. It’s something that points to potential quality control inconsistencies, and it’s worth keeping in mind if you're interested in buying this headphone.

Comparisons

The Cypher lands closest to the Sennheiser HD650/6XX family in overall presentation—particularly when the 6 series headphone has slightly worn pads. It shares that warm, mid-forward character and relaxed treble approach. Compared to the HD600, the Cypher is less bright and less incisive, trading clarity for smoothness and warmth. Against something like the HD550, the Cypher offers a richer, lusher sound, but sacrifices some treble presence and overall balance. When placed next to options like the Hifiman Edition XV, the Cypher is again less prone to treble peaks or "uppy-downy" resonant behavior, but its also less consistent in fit and positioning, with a more subdued overall presentation. 

Final Thoughts

Thieaudio Cypher is a bit of a mixed bag—but an interesting one. Its midrange performance is genuinely excellent, offering a nicely textured presentation that’s rare at this price or tuning type. It blends this with a tuning that's safe, inoffensive, and easy to listen to for long periods.

At the same time, it lacks excitement, struggles with staging, and raises some concerns with build consistency and channel balance. For the right listener—particularly someone who values midrange above all else and is sensitive to treble—it’s a compelling option. For everyone else, it’s harder to recommend outright. 

Sound Score: 5.6 / 10

Overall Score: 5.4 / 10