Fit and Comfort

Seen above is the right channel of the Antlion Audio Kimura Solo and Duo placed into an artificial ear mold with the included size M silicone ear tip installed. I have average-sized ears, and the ear mold above represents my own experiences well enough as a proxy. Size M silicone tips are my go-to for testing, since foam tips are not included by some brands, but you should see what works best for you and don't hesitate to try aftermarket ear tips if you feel none of the provided ones work. The Kimura IEMs are slightly bulbous in that they are larger than typical at the face plate side but narrow down considerably in the ear concha and canals owing to the ergonomic design employed. The ridge at the top can be a love or hate affair when it comes to getting a secure, comfortable fit and the longer, not very wide nozzle helps alleviate any issues in that regard by getting a deeper and isolating seal for most. There are multiple points of contact of the shells with the concha thus and then take your time to orient and hook the cable properly for further support. The angled MMCX connectors help here but you will have to use both hands to get the memory wiring set to your desire. This is all the more relevant on the right side given the boom mic present that you would then naturally direct towards your mouth for better voice pickup. The shells weigh ~6 g each and therefore are not physically fatiguing either.

Audio Performance

Audio Hardware

Antlion Audio is a microphone brand primarily so it was no surprise that we barely get any details on the drivers used in the Kimura Solo and Duo, although there are some microphone capsule specs provided as listed on the first page. I was not able to get much more beyond this either, including the size and composition of the full-range dynamic driver used in both. I can only presume it is the same unit with the Duo adding on a balanced armature driver for further treble extension and clarity. Given the rated impedance and sensitivity numbers provided, the Kimura Solo might actually necessitate a cleaner source without channel imbalance at low volume/gain settings whereas the Kimura Duo should pair better across a wider range of sources. In either case a decent dongle should do fine and a portable DAC/amp would thus be more than plenty when it comes to power requirements. In order to avoid any hissing noises when nothing is playing, I went with the tried and tested Qudelix-5K as well as the Questyle M15 for my listening needs. Seeing also as how I am not in a position to provide you audio clips of how the microphone sounds, I will mention that the Kimura microphone picked up my voice extremely well and on par with my ModMic USB when used over the internet. It's only when you are doing local recordings that you notice the Kimura mic start to clip earlier but it's not really a practice concern. I am plenty happy with the microphone and would happily recommend it already, even outside of the IEMs. I used the cable with a few other IEMs too and kept noticing how people were taken aback by how clear my voice was, with the combination being far easier to travel with as well as not as bulky as headphones. In-line mic controls would have been nice to have though!

Frequency Measurement and Listening

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


Our reproducible testing methodology begins with a calibrated IEC711 audio coupler/artificial ear that IEMs can feed into enough for decent isolation. The audio coupler feeds into a USB sound card, which in turn goes to a laptop that has ARTA and REW running and the earphones connected to the laptop through the Questyle M15 portable DAC/amp. I begin with an impulse measurement to test for signal fidelity, 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, which nets a good balance of detail and noise not being identified as useful data. Also, the default tuning was used for testing, and no app-based settings were chosen unless specifically mentioned. Each sample of interest is tested thrice with separate mounts to account for any fit issues, and an average is taken of the three individual measurements for statistical accuracy. For IEMs, I am also using the appropriate ear mold fitted to the audio coupler for a separate test to compare how the IEMs fare when installed in a pinna geometry instead of just the audio coupler. The raw data is then exported from REW and plotted in OriginPro for easier comparison.


The IEC711 is such that you can't really compare these results with most other test setups, especially those using a head and torso simulator (HATS). The raw dB numbers are also quite contingent on the set volume, gain levels, and sensitivity of the system. What is more useful information is how the left and right channels work across the rated frequency response in both the Kimura Solo and Duo. The left channel was separately tested from the right one, and colored differently for contrast. I did my best to ensure an identical fit for both inside the IEC711 orifice, so note how the two channels are practically identical across the entire useful 20 Hz to 20 kHz range with the Kimura Solo whereas the Kimura Duo has some slight channel imbalance in the 2-4 kHz region that may be where the driver cross-over point is. I could pick up minor imbalance in my ears, especially after having confirmed it was there and I was not just hearing things, and this could be a case of the manufacturing factory needing to step up its QC further. It's not a dealbreaker in itself given the actual discrepancy falls within your standard IEM error bar of +/-3 dB, and I can only speak for this one sample here too. Measurements taken after 35 hours of testing each set, which included these playing a mix of various songs as well as white or pink noise and sine sweeps, showed no difference. There was no perceived burn-in effect thus, and none was measurable, either. The responses with the anthropomorphic pinna in place match the ideal scenarios in the coupler extremely well too and this is an indicator of how good the seal was when installed in the artificial ear.


Here is the average frequency response for both channels of the Antlion Audio Kimura Solo and Duo IEMs plotted against my personal target taken from VSG.squig.link, which also gives you an idea of my personal preferences to better correlate any possible biases. The tuning of a set of headphones or earphones does not have to match my target as long as it is tuned with some direction, makes sense, and is executed well. After all, no one set will appeal to everyone, and having different options is what makes this hobby so interesting and hard to quantify. Indeed, with a slew of Harman-like and warm-neutral tonalities recently thanks to audio brands aiming to appease reviewers and their followings, I was somewhat hoping to see good executions of other tuning styles too. I suppose there's no mistaking what we get here on either set courtesy the clear V-shaped tonality employed!

If you are coming across this review predominantly from your interest of Antlion products from a gaming side of things and are not too privy to the various nuances of headphones and earphone sound signatures, I'll keep this section simple. The tonality of both the Kimura Solo and Duo is referred to as V-shaped because the frequency response is literally shaped like a V. This means that the sound is louder at the lower frequencies, or bass, as well as the higher frequencies (upper mids and treble) compared to the section in the middle. It's the most prevalent mainstream sound signature because people tend to like bass over the rest, at least until they try different styles and then get to see what works best for them. It could still be a V-shaped sound at the end of the day, but it's more likely that your first set of headphones or earphones have been tuned this way. This can be an issue for gaming, however, where you would like to have a more balanced sound to better hear different sounds depending on the game type you play. Footsteps, for example, will mostly present themselves around the 500-800 Hz range with reverberations in a well recorded game coming off at higher frequencies. Likewise, gunshots are typically an impulse shot at lower frequencies that then permeate through the mids and the lower treble.

Unfortunately I can't tell you that the Kimura Solo or Duo even do a V-shaped sound well. The Kimura Solo is the bigger offender in being less detailed throughout and not helping discern between tones at different volumes playing together, also known as how dynamic the IEMs are. This makes for a muddy bass response that especially hurts audiophiles wanting to trying it for music listening, and the tonality also hurts with general media consumption whereby vocals aren't getting their spotlight and neither do most instruments. The sharp ~4.5 kHz peak was quite annoying in my ears too and made for a generally fatiguing set with a treble response that reminded me more of cheap KZ drivers than anything else. The Kimura Duo does improve overall with a slightly more balanced and certainly more bearable tuning, and yet I would not use it for anything beyond electronic music if I had the option. The Duo is more resolving than the Kimura Solo, especially in the mids, but both inherently suffer from weak staging and mediocre imaging to not work well with analytical instrumental playback.

Comparisons

Given the cost of the Kimura IEMs also includes the Kimura microphone itself, it's only fair to compare them against less expensive IEMs as a whole. For the Kimura Solo, especially if you are looking for a similar bass-first sound, there are options in the market from the likes of Tripowin and KZ/CCA although you may want to consider the Truthear x Crinacle ZERO and the QKZ x HBB Khan that provide a more Harman-style tuning with a similar bass-first sound but with much cleaner mids that are far more conducive for gaming and music playback. I'd personally not go with any of these for my library and would much rather tell you to save the cash and go with a balanced budget set of IEMs first to see what you like and dislike. For example, consider going through my review of the Truthear HOLA to see how competitive and excellent the sub-$20 market is these days!


Things are a bit more open with the price range of the Kimura Duo (with the microphone accounted for). You have far more options now in terms of not only single dynamic driver sets such as the Tripowin Olina SE that punches far beyond its pricing point, other hybrid driver sets such as the ThieAudio Legacy 2, or even planar magnetic IEMs such as the 7Hz Salnotes Dioko. Once again I would be hard pressed to choose the Antlion offering for any use case beyond EDM and even here I'd much rather go with the Olina SE and apply a bass shelf for more sub-bass emphasis. There isn't much you are getting with the Antlion Kimura IEMs here over what's already out there, such is the nature of the IEM market in 2023.