Fit and Comfort

Seen above is the ZMF BOKEH placed on a mannequin head to help show how these headphones would look on the human head. Note that the head is slightly under average sized, so account for the discrepancies accordingly. As with all headphones, getting a good fit and seal is crucial, so make sure to properly use the pivot and rotation capabilities of the ear cups and the height adjustability of the headband itself. This section is mostly a summary of the points expanded upon in more detail on the previous page, but I will point out that the BOKEH can weigh 450-510 g, and this feels mostly dependent on the nature of the wood used for the ear cups as opposed to other factors. There is no suede headband available yet, for example, and we don't get a choice of a lighter magnesium chassis here. That said, I was surprised to find this sample to weigh 515 g since I could have sworn it was going to be closer to 450 g based on that range! This tells me the BOKEH, as with the Caldera and Caldera Closed before, wears its weight quite well. The headband strap helps spread out this weight over a larger area and the clamp force was just about perfect for my average-sized head too. The larger ear cups may likely get some attention if you wear it in public, but the associated large, fluted ear pads further help with plenty of room for my ears and a good seal around them—the default pads being thinner than usual might result in some ears hitting the mesh screen though. I had no problems using the BOKEH for 1–2 hours at a time, with breaks afterward, and the BOKEH also offers good passive isolation with minimal sound leakage. If you are used to smaller, lighter headphones and are seeing the BOKEH as an upgrade, then please do be aware the BOKEH is larger and may take some getting used to.

Audio Performance

Audio Hardware

I recommend going through this page to better understand the various ideas and components that went into the patented ZMF Atrium Damping System which is used in the BOKEH. The closed version in the BOKEH should be similar to that used in the Caldera Closed too in that the primary damper is not attached directly to the rear of the driver or to the back of the cup, effectively making it "floating" in the ear cup as seen in this video. The acoustic energy from the dynamic drivers used here is dissipated in combination with the oval BOKEH ear cup design, allowing for more control over back-wave damping and the eventual tonality of the headphones by optimizing the airflow behind and delivering it in a more controlled manner to the ear canals. The closed ADS technology also minimizes standing waves and allows for a more natural decay of sound so that soundstage and timbre still feels natural. Speaking of the drivers themselves, the BOKEH uses 50 mm diameter liquid crystalline polymer (LCP) diaphragm dynamic drivers which are not manufactured in-house. The lighter, snappier diaphragm was deemed to be more suitable with a relatively low—for ZMF—impedance voice coil, making the BOKEH more easily driven than the higher impedance dynamic driver sets ZMF is famous for. At 80 Ω and with a rated sensitivity of 103 dB/mW thanks to some high efficiency neodymium N52 magnets, the BOKEH is quite easy to drive even from a portable DAC/amp such as the Cayin RU7 or FiiO KA17, let alone more powerful DAPs and other larger mobile sources. It should still scale reasonably with more powerful desktop gear, but you won't be held back notably here to where the BOKEH can be a more transportable set if you travel a lot.

Frequency Response Measurement and Listening

I will mention that I have a general preference for a warm-neutral signature emphasizing a slightly elevated bass and smooth treble range with detailed mids and good tonal separation. I also generally prefer instrumental music over vocals, with favored genres including jazz and classical music.


Our current headphones test setup uses a set of two custom in-ear microphones for the two channels. These microphones closely adhere to the IEC711 class, but have been tweaked to be more reliable in the >10 kHz frequency range, the precise issue with my previous setup, that is otherwise still very good and will continue to be used for IEMs and earphones. Two soft silicone pinnae are installed on the sides, separated by a distance matching my head, and multiple "height" adapters have been 3D-printed for further customization, based on fit, head size and shape. Each set of microphones has an XLR output I separately adapted to 3.5 mm. I used a transparent source—the FiiO K19—for measurements after confirming it was not a bottleneck in any way, but also used a DAP, as seen above, to confirm it was no different for this purpose. This artificial head simulator feeds the microphone lines into a reference USB sound card, which in turn goes to a laptop that has ARTA and REW running. I begin with an impulse measurement to test for signal fidelity, FFT to test for headphone seal, calibrate the sound card and channel output, account for floor noise, and finally test the frequency response of each channel separately. Octave smoothing is at the 1/12th setting, netting a good balance of detail and signal-to-noise ratio. The default tuning was used for testing, and no app or program-based EQ settings were chosen, unless specifically mentioned. Each sample of interest is measured at least thrice with separate mounts to account for any fit issues, and an average is taken of the individual measurements for statistical accuracy.


As per usual, you can find my headphone frequency response measurements on VSG.squig.link, along with all the earphone measurements. Scroll to the bottom and choose different targets there, including two from Harman Kardon, developed after years of R&D. Those who have read my headphone reviews would have noted how I typically go for the "Harman Combined" target based off the Harman 2018 over-ear target but with the lower bass target from the Harman 2013 curve instead. I prefer this for open-back sets which it feels far more natural to me, but I refer to the full over-ear Harman target for closed-back sets owing to that bass shelf energy they tend to have. This is not to say that I want headphones to be tuned to this target though—what matters in the end is whether the headphones are tuned with sensible direction and the tonality is executed well. After all, there are always personal preferences and what matters more is how a pair of headphones ultimately sounds to you. I also like what ZMF had to say about how drivers have an innate tuning which works best for each specific driver setup, so what the team there set out to achieve with the BOKEH is effectively to get the best of the LCP drivers + that lighter voice coil, with the ADS system helping achieve as much. First up, take a look at the excellent channel matching achieved here throughout the entire frequency range. Keep in mind that pads and how the set is mounted on the rig also affects measurements, let alone the use of a non-industry standard setup, but I never noticed any imbalance in the ears. This is a demo unit, so I don't even know if this is B-stock or one specifically marked for reviews, but either way I understand it would have gone through the same multiple levels of inspection on an industry standard rig and on-ear testing as any retail set of ZMF headphones do. Also, while not the norm at all, this LCP driver did seem to open up in the bass and with a smoother bass-to-mids transition over the 200+ hours of testing. Call it brain burn-in perhaps, but I have to say what I felt even with new pads throughout.

At this point, I'll mention that the measurements above lined up fairly well with how I heard the BOKEH, which is to say very snappy and engaging bass, slightly relaxed upper mids compared to the Harman preference target seen above, and then a relatively relaxed sound in the treble with some peaks and dips but nothing fatiguing. I will also say that the upper mids were slightly more filled in the 1-2 kHz region for my ears than the measurements above indicate, and the dip at ~9 kHz is more pronounced than the graphs might suggest. The drivers are placed slightly offset in the ear cups, so that is likely why the measurements differ from my experience despite me trying different mounts. But yeah, the BOKEH is probably the one ZMF set which comes closest to Harman tuning of any I have heard so far—I can see a certain audio forum preferring it over, say, the $3500 Caldera Closed just for that. At the same time, I have no qualms in saying that the first 15 min with the BOKEH were just more fun and engaging for me than even the Caldera Closed, and I had the opportunity to listen to both for the first time alongside one another since they arrived in the same shipment. The Caldera Closed then stretches its legs and showcases its increased resolution and instrumental accuracy, but the BOKEH is no slouch for pure bassheads and those who appreciate a natural timbre. The BOKEH has a decidedly warm tuning which might feel "organic" for some too, but thankfully doesn't have any bass bloat or mids interference. There's the tiniest of sub-bass dips under 40 Hz with the stock pads, but the mid-bass is easily the selling feature here. It's in your face, it hits hard, it's plenty dynamic, it's got that "boom boom" sound in the words of my partner. This is achieved without going for a decidedly V-shaped tuning either, although I'd still say brass instruments and rock/metal music fares better on the BOKEH than some vocals and string instruments do.

The BOKEH isn't the most resolving set on the market, but I dare say ZMF isn't necessarily known for that in the first place. The Caldera and Caldera Closed certainly challenge the detail retrieval kings, yet the BOKEH is more on the groovy train instead. If the goal was to be able to lose yourself in the music with the BOKEH on, it certainly does the job. I can have a tiny portable DAC/amp in my pocket, or even have a Bluetooth source taped to the cups, and have a taste of that ZMF timbre. Acoustic jazz, pop, and country music vocals are still prominent here though, which is how you know the BOKEH is still tuned competently and not just colored for the sake of it. Some female artists may feel slightly recessed compared to brass instruments, but the odds of this happening simultaneously are uncommon—especially in the average user's music library. The upper mids and lower treble are relatively relaxed, making for the bass to be more prominent, which contributes to some of this more laid-back presentation. The positive here is no fatigue or sibilance, although I did find imaging to take a slight hit outside a sharp cone in the front. The BOKEH sounds spacious enough too, so there are no closed-back intimate sound issues here, and neither did I find any built-up pressure in the ear canals as a result. I would personally want a touch more 1-2 kHz upper mids and a bit more treble, especially for my orchestral collection. I am not sure the BOKEH drivers are necessarily the best for the higher frequencies, but it was still nice to have the trailing ends of tones be more pronounced than usual. Clarinets and harps in particular, and piano keys too, had that lingering sound that I don't typically get with planar magnetic drivers. Some of this has to do with the Atrium damping system no doubt, but in particular you'd notice a transient response here that is longer than with typical planar magnetic drivers—even the Caldera drivers that somewhat buck this trend. The end result is evident enough—If you like a warm and relaxed sound with dynamic and textured bass, the ZMF BOKEH should be near the top of your consideration list.