In this feature, Nihal reviews the Jomo Audio 408H Skyline, which is a high-end dual 9.7mm PET dynamic and 6 BA driver hybrid universal and custom in-ear monitor.
Disclaimer: This sample was sent to me in exchange for my honest opinion. Headfonics is an independent website with no affiliate links or status. I thank Jomo Audio for this opportunity.
Click here to learn more about Jomo Audio products that we have previously featured on Headfonics.
Note, that this article follows our current scoring guidelines which you can read in more detail here.
Jomo Audio is a well-established brand from Singapore and has been at the forefront of IEM design and manufacturing for a decade.
Founded by Joseph Mou, Jomo Audio consistently delivers high-quality IEMs, continuously advancing technology with each new release. They have put a lot of focus on IEM designs, manufacturing techniques, and tuning methodology to produce some popular IEMs.
At Headfonics, we’ve reviewed several IEMs from Jomo Audio going back almost 10 years ago with the Jomo Audio 6. The most recent review, posted by Josh, featured the Jomo Audio S100 Cappuccino. Let’s find out what the new Jomo Skyline offers.
Features
The Jomo Audio 408H Skyline is a universal hybrid IEM featuring 2 custom 9.7mm PET diaphragm dynamic driver units and 6 high-precision balanced armature driver units.
The driver implementation on the 408H Skyline has been borrowed from the other Jomo flagship IEMs. The IEM has the two dynamic drivers placed face to face in a special proprietary 3D-printed A.C.C. acoustic chamber. This chamber design gently lowers high-frequency sounds for a smoother output.
It also has six balanced armature drivers split into three groups for mid, mid-high, and high frequencies. The IEM employs a proprietary C.S.U. (Cross Sync Uniphase) crossover network that fine-tunes each group for frequency and phase by orchestrating synchronized collaboration among the drivers.
This creates a far more coherent and natural-sounding performance with a balanced mix of strong bass, rich mid-tones, and clear high notes.
Design
The shells of 408H Skyline are built from acrylic resin. The IEM is available in both custom and universal designs. The one that I am reviewing is universal; however, the design resembles a custom fit due to its nice, easy fit.
The body of the IEM shells is black, and the faceplate features sparkling purple flake scatters. The glittery starry finish on the faceplates does a nice justice to the name.
On top of the faceplate, you will find the letters “JM” or Jomo Audio’s logo, written in silver on one side and “Skyline” written on the other. The IEM is well-constructed with a comfortable, ergonomic design.
Comfort & Isolation
The Jomo Audio 408H Skyline features a design inspired by CIEMs, providing a comfortable fit. The relatively small shells are designed to sit easily in the ears. The nozzle is of average length but slightly wider in diameter than usual, ensuring a snug fit for most average-sized ear canals.
For me, the fit is almost flush, and the IEM hardly sticks out of the ear. When on the move, these IEMs stick to their insert positions and do not fall off or become loose.
Adding to the design, the corners on the shells are quite nicely finished, devoid of any sharp corners or pressure points. The shells are lightweight, which further adds to the comfort. I find the IEM quite ideal for longer sessions.
Each shell has a vent to relieve pressure buildup when using the IEM, enhancing the comfort factor. Additionally, I haven’t experienced any instances of driver flex with these IEMs.
Thanks to the nice and snug fit and the design of the shells, the IEMs are quite good at blocking outside noise and have a good isolation factor.
Ear Tips
Jomo Audio provides a nice set of ear tips of multiple shapes and sizes with the 408H Skyline. Most of these ear tips have wide bore and short stems.
There are two different sets of silicon tips, one with a single flange and the other with a double flange. The single-flange tips come in different colors, and the double-flange tips are black only.
In terms of fit, these tips have decent seals. The double flange tips, which have a thicker body, are not as comfortable as the single flange tips.
Stock Cable
The stock cable on the 408H Skyline comes in black and has a 4-wire configuration. The cable comes with 2-pin connectors that feed into the IEM shell. The cable ends in a small, 4.4mm right-angle adapter jack with good strain relief. At the Y-split, it features a compact black barrel branded with the Jomo logo.
This cable is quite thin and has a very supple character. I am not particularly fond of the ultra-thin and flimsy build. For the price of the IEM, users may expect a better build.
I was initially apprehensive of the synergy of this cable; however, from a sound performance perspective, this cable does its job just fine.
Packaging & Accessories
The 408H Skyline comes in generous packaging, which most of the users will find value for money. Jomo has spared no effort to ensure an impressive presentation.
The outer case is huge compared to the offerings we generally come across. This case is built in carbon fiber and has metal components. Atop the case, the silver Jomo Audio branding adds a touch of elegance.
The inner walls of the case are covered in protective soft foam. Upon opening the box, one is greeted with two separate compartments, one housing a leather case and the other containing some other accessories.
The leather case contains the IEMs and the cable. Other accessories include a cleaning cloth, a pack of ear tips in a small plastic box, a small velvet pouch, a mesh drawstring, and a Jomo Audio sticker.
The leather case comes in black and has a Jomo logo engraved on the top. There is enough space to pack the IEMs with the cable.
The inner foam cutouts of the outer box can be removed to use the space to store more things. Since the size is quite large, one can store their DAPs and many other products in the carry case.
Sound Impressions
The following sound impressions of the Jomo 408H Skyline were completed using a mixture of my main source, Lotoo’s Paw Gold Touch, Astell & Kern SP3000, and occasionally the Earmen Angel DAC/amp. I paired the IEMs with stock cable and Azla SednaFit Light ear tips, size MS.
Summary
To begin with, the Jomo 408H Skyline has a v-shaped tuning and quite an energetic sound profile with a hint of brightness.
The sound strikes a decent balance between fun and technical. Two distinct features stand out for me – one being a satisfying low end, and the other being the highly resolving capabilities of the IEM.
Bass
With 2 dynamic drivers in place, one can expect decent bass production from the 408H Skyline. The bass is quite clean, with good layering and texture. There is an emphasis on quality while maintaining a decent quantity.
The 408H Skyline has a nice balance in how the mid-bass and sub-bass are produced. You will not feel one overly emphasized over the other. The sub-bass impresses with its depth and impactful presence, offering a satisfying experience.
The mid-bass delivers sufficient punch and has a good body; however, it may come across as lacking from a basshead’s perspective. The bass excels at dynamically responding to tracks that demand a heavier bass line, showcasing the versatility of the low-end tuning.
In general, this bass definition proves ideal for casual listening sessions, offering a balanced experience without overwhelming bass levels.
Midrange
In the midrange frequencies, the emphasis leans towards clarity and resolution rather than prioritizing lushness. The midrange is characterized by a focus on articulating individual elements with precision and detail rather than imparting a warm, rich tonality.
One can expect a crisp and very sharply defined presentation, which promotes a transparent listening experience. This midrange lacks density and a rounded body and may come across as dry to those who love lush and rich mids.
The lower mids do not get any added benefit from the bass region, thus missing the lushness and warmth. There is a linearity in the way the midrange is rendered.
The midrange is energetic, and the upper midrange has a hint of extra energy, which sometimes may come across as sibilant or harsh depending on the source chosen.
The midrange sound has a lot to do with the type of source you choose. On the Lotoo Paw Touch Gold, the midrange frequencies exhibit a decent tonality, contributing to a sense of weight and warmth in the overall sound profile.
This adds to the pleasing depth and fullness of vocals and instruments. The SP3000 leans towards a brighter and potentially more analytical sound and less weight.
Treble
The treble on the 408H Skyline is the star of the show. This is one of the best treble ranges I have come across in the IEMs of this price range. The resolution and detailing in the treble region are quite good.
The IEM accurately reproduces the shimmering and transient nature of cymbals, allowing one to distinguish the distinct sound of each strike along with the subtle nuances of their decay.
There is a decent level of energy in the upper frequencies, which creates a good sense of airiness. Its crystal-clear treble response and resolution nearly rival those of EST drivers, ensuring that even the most delicate performances are faithfully reproduced without compromise.
The treble is, however, borderline sharp or sibilant, potentially presenting a slight challenge for sensitive listeners. The choice of source is really important. Cable-rolling also comes in handy for taming the treble a bit.
Staging & Dynamics
The soundstage on the 408H Skyline is more in-depth than in width. There is a good sense of spaciousness. The stage spreads more in the front-back direction than sideways. With a decent power source, the stage spreads further.
The BA drivers on the 408H Skyline are tuned to give very high precision and resolution, which is rightly achieved too. The IEM excels at retrieving intricate details present in the music with nice clarity.
The layering and separation of instruments on the 408H Skyline are done very well. On busy musical passages, there is enough breathing space and no feeling of congestion.
The imaging is notably precise, allowing each element to be heard distinctly without blending into one another, resulting in an accurate reproduction of spatial characteristics.
Click on page 2 below for my recommended pairings and selected comparisons.
