Fit and Comfort

Little differentiates the three included ear tip types front-on. As such, I used the single representative image above for an example size M ear tip installed on the right IEM and inserted into an artificial ear mold. 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. Then there is the issue with the cable itself, whereby the most natural fit position with the IEMs for me did not allow the cable connector to naturally flow over and around the back of the ears. Instead, the angled connector housing forces a steeper exit at the top of the ears itself, which can only be rectified with a less comfortable fit. I did see some example fits of this IEM/cable combination in eastern Asian ears cooperate better, so take that for what you will as I can only speak about my own experiences. A replacement cable won't be a bad idea thus, perhaps even one with replaceable plugs on the other end. Regardless, once fit in, you will find the EJ07M quite comfortable relative to the average tribrid IEM, although the metal shells may initially feel too cool in the winter. These have a generally ergonomic fit in the concha, and the single vent makes for a good balance of passive isolation and pressure balance inside. The IEMs weigh more than average at just under 9 g each owing to the metal shells, which is still plenty fine as it isn't physically fatiguing for hours on end.

Audio Performance

Audio Hardware

LETSHUOER has no graphics to go over the driver distribution for the EJ07M, which is a shame given it has one of the most interesting and unique driver sets. On the plus side, an actual video does go through the making of the EJ07M, which is even better! As mentioned before, it is a tribrid set, so three different types of drivers are used. A custom 10 mm nanocarbon-coated membrane diaphragm dynamic driver is used to handle the bass response, with two Sonion 2389 balanced armature drivers employed for the middle frequencies, which leaves a whopping four Sonion EST65QB02 electrostatic (electret) tweeter drivers for the high frequencies, which is twice as many as the other two tribrid IEMs reviewed to date.

It may thus seem that driving the hardware would be hard, but it ends up not so with straight up average values for both rated impedance (19 Ω) and sensitivity (107 dB/mW), although LETSHUOER may want to check the packaging as it cites a sensitivity of 107 dB/W instead! This makes the EJ07M no harder or easier to driver than the vast majority of other IEMs on the market—a standalone DAC/amp isn't really needed. That said, going with one of the portable Bluetooth options we have covered before also makes this a wireless solution, and the lack of a 3.5 mm audio jack for most phones these days is another reason to consider a DAC/amp for portable use. If not on the go, space is less of an issue, but the relatively short cable might still be a potential handicap if connecting to a PC as the audio source, though it is slightly longer than the average IEM cable at 1.25 m. I was able to get plenty of juice from my laptop's Realtek audio codec-powered 3.5 mm jack even with the volume in Windows set to 50%.

Frequency 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 reproducible testing methodology begins with a calibrated IEC711 audio coupler/artificial ear 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 sound card. 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 and not 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 the LETSHUOER EJ07M, or at least the useful part of it. 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 identical for all intents and purposes. Given that reviewers such as myself get a randomly chosen single sample more often than not, the best way to test for driver reproduction and consistency is by comparing the two channels to each other, and this might be the closest anyone has come yet! Measurements taken after 50 hours of testing, including with these playing a mix of various songs as well as white or pink noise and sine sweeps showed no differences, either. There was no perceived burn-in effect thus, and none was measurable. The response with the artificial pinna in place matches the ideal scenario in the coupler very well, including with the typically seen resonance shift, although the fit issues with the cable may be causing the slight bass response drop here.


This is the average frequency response for both channels of the LETSHUOER EJ07M 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. That being said, this set is obviously tuned with a U-shaped signature in mind, and I think it's a very good set as both an objective reviewer and personally having it appeal to my interests.

Look, you all know how much I gushed over the ThieAudio Monarch (MK.1) at a time when I was only starting to get to know the wacky world of IEMs, and I have since listened to and tested several more IEMs in various price ranges on either side. I still think the ThieAudio Monarch is one of the very best ever made, and the LETSHUOER EJ07M might be right up there with it. Tonally, the EJ07M seems to have actual monitoring and accuracy in mind, with a clear-cut sub-bass lift of ~12 dB from ~200 MHz, which is plenty in itself but concentrated to allow for contrast galore from the mids. I am no EDM connoisseur, but everyone I trust to be confirmed that the EJ07M is excellent for it. I see this helping aplenty with bass guitar notes, too, with each note in the 50–150 Hz range with impact behind it that decays fairly quickly to make room for the next one. It's still a touch too much bass for me, so I found myself EQing it by around -4 dB, which the EJ07M handled like a champ.

As the frequency response graph clearly shows, the bass does not bleed into the mids, and the extended mids are a strong point for artists and music mixing alike, with so much range making instruments and vocals shine harmoniously. Male vocals may come off somewhat backward-facing, so keep that in mind if you listen to a lot of music with male vocals in a mix of instruments, say country or even classical rock. Technically, the EJ07M does a fine job, but is not class-leading in the price range it operates in. Imaging in particular could be improved, whereby I felt there was a strong zone on either side of my head closer to the drivers, but not as much elsewhere. This is compounded by a wider than taller or deeper soundstage, which did occasionally keep me from enjoying the latest from the New York Philharmonic, and the rest of the big five.

The rise into the upper mids might be contentious for many, but HRTS enthusiasts will like the earlier rise in a slow, controlled manner from ~800 Hz for the natural presentation of female vocals without them being weak or shouty, while also accounting for pinna gain very well. It might be a touch less than what some may want, however, especially with the 5 kHz shoulder that can make for a problematic region with some instrument fundamentals. In fact, such is the community of EJ07M owners that there have been suggested mods, including adding a second set of filters from Tanchjim in particular to alleviate a potentially bright treble response for treble-sensitive folks. I can see the logic behind this, but tip-rolling with a deeper fit (foam or otherwise) can also have a positive effect here. Ultimately, it's the use of four electrets that makes for a nicely controlled treble extension in my books, allowing for even second-harmonics from string instruments as well as cymbals and triangles.

Comparisons

The obvious comparison has to be with the other two tribrid IEMs reviewed thus far, the ThieAudio Monarch and XENNS UP, both of which cost more than the LETSHUOER EJ07M by a decent margin. If money were no object, I would pick the Monarch every single time, but it costs over $100 more than the EJ07M that probably will do better for most audiophiles than the analytical Monarch. It's only in the technical department that the EJ07M is found more wanting since I would be hard-pressed to choose the XENNS UP over the EJ07M. The metal shell and smaller footprint also make the EJ07M physically more comfortable to wear and listen to without worrying too much about build quality, and that is a benefit never to be ignored. The others do come with more tip options, but that is not enough to change the outcome of this comparison.


There are plenty of bass-boosted IEMs out there, including several I have already reviewed. Once again, I point you towards VSG.squig.link to compare them all with the EJ07M, but am showing off two IEMs that cost less but have a few tonality challenges to where owners of these IEMs, or similar ones, might be interested in the EJ07M for a future upgrade. It retains the bass boost you got those original IEMs for in the first place, so you will not have to sacrifice that. What you get in return for the extra money is a more balanced set throughout, in addition to more air in the high frequencies and arguably better technical performance. The HarmonicDyne P.D.1 in particular is the letdown here I would rather urge owners to sell to recoup as much money as possible and save up for something, such as this LETSHUOER EJ07M.