Introduction

The never-ending march of planar IEMs continues! While our first such entry was with the kilobuck range Audeze Euclid and there have been plenty of misses along the way, it wasn’t until the 7Hz Timeless that people saw a well-tuned set of planar magnetic drivers used in in-ear monitors at a reasonable cost. Then came the LETSHUOER S12 using a version of the same drivers in a much more amenable form factor and cost and the floodgates opened thereafter with entries from MUSE HiFi and many others. All of these seemed to rely on the same OEM drivers and it took until very recently for the likes of DUNU and MOONDROP to come up with their own sets, engineered from the ground up.

Today we examine the MOONDROP STELLARIS that aims to take on the likes of the 7Hz Salnotes Dioko, in offering exceptional value for money. The Stellaris effectively replaces the MOONDROP Starfield, hence also the space theme and design here, and uses custom-developed planar magnetic drivers in a fairly unique form factor. MOONDROP promises planar speed and accuracy, along with exceptional detail and ultra-low distortion, as well as a more nature timbre that pretty much any planar magnetic set generally loses out when compared to dynamic drivers. Thanks to SHENZHENAUDIO for providing a review sample to TechPowerUp as we aim to put these claims to the test today, beginning with a look at the product specifications in the table below.

Packaging and Accessories

Anyone remotely familiar with MOONDROP products knows to expect a so-called “waifu” on the product box, and a new one at that. The STELLARIS is no exception, and I suppose the poor rendition of the feet here serves as a warning as to how—spoiler alert—the designers of this product probably don’t understand how some things work. The front also has the company and product name whereas on the back is actually useful information about the product, including a factory frequency response curve and a diagram showing the various parts that make up these IEMs. There is an inner cardboard box which slides out of the sleeve and it has the items available for retrieval right away. These include the STELLARIS shells snugly protected by thick foam, and separate compartments for the various accessories. MOONDROP provides plenty of paperwork in the form of a contact card, a QC verification card, and a quick start guide going over how best to use IEMs if you are not familiar with them. There’s also a STELLARIS-themed postcard too, if you were a fan of the artwork on the box but didn’t want to keep the packaging. Everything else comes in individual plastic zip-lock bags, as seen above.

MOONDROP throws in two types of ear tips with the STELLARIS in the form of its MIS sponge foam tips in sizes S/M/L and also the expensive Softear Ultra Clear silicone tips in the same three sizes. The latter is developed by MOONDROP’s sister brand Softears, and is similar to the AZLA SednaEarfit XELASTEC tips in being somewhat tacky to the touch, and lightly malleable based on a narrow temperature range to allow them to better fit your warmer ear canals. The carry case is very similar to that shipped with the MOONDROP KATO, except in all blue without the gray accent strip along the front. As is common in this price range, it is made out of faux leather and yet looks/feels nice enough, down to the stitching. The zipper is sturdy to where it won’t fall off anytime soon and is easy to use. The MOONDROP logo is etched into the front, and the lid is held in place by a single magnet. The case has soft lining inside, along with ample room for both the IEMs and cable to be stored.

Closer Look

MOONDROP shares next to no information about the cable, which is a shame. It begins with a right-angled 3.5 mm TRS single-ended plug headed to your source, and tied to blue-colored plastic housing. The cable is probably re-used from the likes of the Aria Snow Edition, in which case it should be using high-purity 6N (99.9999%) oxygen-free copper as the conductor, that in turn gets silver-plating. The STELLARIS clearly employs a blue and gold color scheme so it’s nice to see MOONDROP having gone the extra step to color-coordinate the sleeving of the individual braids that in turn come inside a clear sheath. The splitter is the exact same circular plastic bead that was used on the cheaper Chu and Aria cables, except again in blue. There is a gold-colored cable cinch here which doesn’t go a great job unfortunately. Furthermore, there is a highly curved set of pre-formed ear hooks which then lead to two 0.78 mm 2-pin connectors that have hard-to-see L/R markings on the see-through housings, in addition to a red ring on the right side for channel identification. The metal plugs are gold-plated for oxidation resistance. It’s not the best cable I’ve used in being harder to reshape, prone to kinks, and slightly microphonic.

The MOONDROP STELLARIS shells are impressive in more ways than one. They are massive in both size and weight, taking up nearly 14 g each and reminding me of the IKKO OH10 IEMs with their copper shells. MOONDROP is using thick metal here—presumably brass—and the shape of the shells is also similar to some of the sister brand Softear IEMs with the pill-shaped faceplates that have a rather large housing and even larger nozzle behind. The shells get an iridescent finish that goes from muted to striking colors based on the incident light and the base blue color helps contrast the intricate sun and stars design in gold. MOONDROP claims these are hand-painted, but I find that hard to believe. The gold colored vents on the face plates are just decorative screws that MOONDROP has seemingly tried to patent for whatever reason. There’s a lot of things going on here which make little sense to me! Note also the recessed 2-pin cable socket located at the top rather than the sides, with “STELLARIS” and L/R markers on the sides instead. We then make our way to that highly angular and thick, two-step nozzle that is already ~6.3 mm at the ends and has no filter, with MOONDROP instead going with foam inside for dampening as well as minor protection of the acoustic chamber from contaminants.

Seen above are both types of included ear tips in size M installed on the right shell—both have relatively larger bores. As mentioned previously, do try them all out and see what works best for you. Note that you may also end up having different sizes for the two ears depending on the size of your ear canal, given these biological features won’t necessarily be the same for everyone. The Ultra Clear tips are tackier in grip, and mold better to the inside of the ear canal in my opinion. There is no retaining lip on the nozzle although you have to spread the tip bore slightly to fit over the nozzle anyway, thus retaining them in place via pressure once you get them all the way down the smaller nozzle section. Installing the cable is simple enough, with the pre-molded ear hooks that go over the ears and L/R indicators helping identify what goes where. Push the 0.78 mm 2-pin plugs into the IEM connectors as seen above, and friction will do the rest in keeping them in place. One thing I will note here is the blue plastic on the cable housings does not match the blue on the shells, but that’s a small issue compared to what’s coming up.

Fit and Audio Performance

Seen above is the right side of the MOONDROP STELLARIS installed in an anthropomorphic pinna that does well in showing my own experience with these. I have average-sized ears, and found the size M Ultra Clear tips to work best. The huge shells, the unfriendly nozzle, and the cable connection at all the top all come together to make the STELLARIS one of the worst fitting IEMs I have ever tried. It hangs looser than I’d like, with the majority of the shell not seated in the concha to where the ear hooks in the cable are basically useless in terms of providing additional support. The heavier nature of the shells makes this worse in pulling the shells down by gravity. You can force these in further down the nozzle for a more secure fit but then the thicker nozzles result in discomfort too. The very nature of the fit being angled nearly opposite to every other ergonomically-designed set of IEMs is where I can confidently say MOONDROP needs to go back to the drawing board on this. There’s no point in getting a set you can’t wear comfortably and use properly. I will say that isolation is fairly good though so, if the sound signature was exceptional, there would be merit to using the fit in the ear canals combined by using the cable cinch to lift the IEMs from the cable and keep them in place that way.

Aiding in the goal of achieving a must-have sound in the price range of the STELLARIS is MOONDROP’s collaboration with Tuoyin Electronics Co., Ltd.—the first Chinese manufacturer to develop planar magnetic drivers, with over 20 years of experience in the game. The two brands worked together to produce a 14.5 mm full-range planar magnetic driver that sounds similar to other 14.x mm drivers everyone else is using but from a different manufacturer altogether. MOONDROP is also taking some creative liberty in marketing here by claiming a “sub nanometer diaphragm” but then goes on to say the diaphragm goes as thin as 1 µm which is not even sub micrometer! There’s a 2 µm thick trace applied in a single coil pattern to maximize contact area, and the transducer uses double-sided magnet arrays with seven N52H-class magnets per side for uniform driving force, and making for a low distortion driver. These come together to make the STELLARIS slightly more demanding than the average set of IEMs, with a rated impedance of 36 Ω and sensitivity of 117 dB/Vrms (102.5 dB/mW). A decent portable DAC/amp will not be a bad idea here and I paired it with the Qudelix-5K and Questyle M15 for most of my listening experience.

Testing was done similar to all other IEMs, such as the recently reviewed MOONDROP Chu. Seen above is the measured frequency response for both channels of the STELLARIS, which can be inspected further here if interested. Keep in mind that expectations are high not only from MOONDROP’s history as an IEM manufacturer, it’s own lofty marketing claims, and also the part where the poor fit simply has to be offset by both good tuning and technical performance to justify the STELLARIS’s presence in the burgeoning planar IEM market. Unfortunately, I have to say things don’t pan out well, with what comes off to be a heavily undamped sound signature that’s extremely bright even to my ears. Indeed, there have have been quick mods by others involving additional filters on the nozzle which help, but nothing will stop the sound signature of the STELLARIS to be anything but bright/shouty bordering on ringing and shrieky even. I am not sure what MOONDROP was even thinking, releasing this set with an >18 dB peak in the air region that made me take this out immediately once I had cymbal clashes in the picture. The other issue is the ear gain presented in the upper mids ends up going past even the diffuse field target to where female vocals are also going to come off poorly represented. These are bigger issues than you’d think since EQ’ing the peaks down with a related preamp also lowers the bass and mids proper, to where those can be less-than-audible when the treble region is more managed. This is even assuming you get it down properly since it’s a play-by-ear thing and not everyone will perceive this peaks the same way.

It’s a shame because, at its core, these drivers are actually good in terms of resolution and even macrodynamics. Indeed, isolated purely to the bass, the STELLARIS is, well, stellar. There’s a fairly substantial ~9.5 dB rise in bass going from ~500 Hz down to allow for a U-shaped tuning here and the set slams hard with a good seal. It also takes EQ quite well here to where you can go even further with a bass shelf and get good rumble going on to electronic music. The added warmth in the upper bass and lower mids also lends favorably here to rock music in addition to forward-facing male vocals. Timbre is slightly metallic and yet on the better side of average for planar IEMs I’ve tested to date. So there is clearly something here that MOONDROP could have realized, had they taken more time in the R&D and preliminary feedback phase, and iterated to justify the wonky fit and comfort issues. I just don’t realize why anyone greenlit this product in the current version. I should also note that, should you so be inclined to cram this in further in the ear canals to achieve a better and more secure fit, the unpleasant treble response gets more emphasized to where it almost punishes you, no matter what you try to get around the physical fit and comfort issues.

For context, I have the STELLARIS compared to the 7Hz Salnotes Dioko it directly competes against, as well as the LETSHUOER S12 and TangZu Audio Zetian Wu that are also planar IEMs which come close to the selling price of the STELLARIS during the various sales they go on. Interestingly, the Dioko had a first batch that had similar tonality as the STELLARIS, in that it wasn’t damped enough in the higher frequencies, but that was unintentional and quickly fixed. The other two sets are also easily better than the STELLARIS almost every which way except for detail retrieval and dynamics, but they at least fit well enough to be usable! MOONDROP on the other hand have had a weak series of releases of late when it comes to IEMs (Aria Snow Edition, STELLARIS), headphones (Void being taken off retail launch at the last minute, delayed MoonZero and Venus), and even sources (MoonRiver 2 quite expensive for what you get). Let’s not even forget that painted MOONDROP shells have been chipping more often than not, to where I am not even confident the finish on the shells will last. Frankly I don’t see a good reason to spend the $109.99 that MOONDROP asks for the STELLARIS from distributors such as SHENZHENAUDIO who have been great in not asking me to change this review, despite the clearly negative tone here. I’ll give them props for this and want to see MOONDROP do to the STELLARIS what they did with the VOID too—take it back before its too late and try again. There is clear potential with these drivers, and they deserve better.