See link to YouTube review at the end of this post!
Overview
I did not need another set of in-ear monitors (IEMs), but after having reviewed Bluetooth wireless earphones with xMEMS drivers and having good experiences with them, I was interested in adding a wired set with the same drivers to my collection. The Halcyon have a dynamic driver, three balanced armature (BA) drivers, and one MEMS driver. The dynamic driver covers the low-end frequencies, and the BA and MEMS drivers handle upper mids and highs. The primary advantage of MEMS drivers over BAs is that they take up less space, respond faster, are more efficient, and produce less distortion.
Hardware/Design
If you like silver, you'll probably like the look of the Halcyon. The bodies have a dark metallic semi-matte finish that sits somewhere between chrome and gunmetal. The face plates are a little bit shinier with tiny KE lettering in a darker gray embossed across it.
To me, a person who prefers gold over silver, they look fine. They aren't too flashy, but they also don't look cheap. They also don't look as large as some other multi-driver in-ear monitors, like my Raptgo Hook-X.
The two-pin connector is placed on top as you'd expect and the included cable is a coppery affair that isn't too stiff, even at the ear hooks, which are reinforced with a pre-formed plastic covering to allow them to curve around your ears. The cable has a black chin slider that stays in place pretty well. The cable termination is modular, and you get 3.5mm single-ended and 6.3mm balanced connectors in the package. The cable isn't one that I would have chosen for the Halcyon; I would have opted for a cable that is silver to better match, but it works fine and doesn't present too much noise when handling it.
Comfort
Ultimately, you can replace a cable that you don't like but if the earphone bodies don't work for your ears, nothing else really matters. And although I eagerly ordered these via the Kiwi Ears Kickstarter campaign simply because they were IEMs with MEMS drivers and they didn't look too huge for my ears, it turns out this is really tough to gauge via pictures. On its face (literally), the Halcyon look smaller than my Raptgo Hook-X, which are the largest non-custom IEMs I own. But the difference maker is its overall shape. The Hook-X are larger vertically, but the Halcyon are larger horizontally and they are just a bit too wide to fit comfortably in my ears for extended periods. I can wear them for about an hour before I start to feel discomfort. So, the Halcyon are not an all-day option for me. If your ears are wider than mine, you'll probably fare better with the fit of the Halcyon.
Accessories
I ordered the S-Link microphone USB C cable with my Halcyon order because I didn’t already have a 0.78mm two-pin USB C cable with a microphone that I could use regularly. I had an older Kinera cable that I had attached to my KZ ZS10 IEMs, but I’d damaged one of the cables so although it still worked, I didn’t trust it to use it on a regular basis. Having a cable with a microphone meant I could use it with my phone and still be able to take phone calls, hopefully with good voice quality. I find the S-Link cable usable but the DAC that’s built into the cable isn't top quality. I'd say this cable is best used for calls. If you want to do critical listening, stick to the stock cable. The cable actually has two microphones; a boom microphone complete with foam cover and an inline microphone with volume and play/pause controls. The boom microphone is removable and once removed, the inline microphone takes over. Both microphones will pick up your voice well but will also pick up a lot of background noise. You’ll want to use either microphone in a quiet environment for best results.
The S-Link cable is a whitish-silver and does match the Halcyon a bit better than the stock cable, but it's a thinner cable that doesn't feel quite as robust. As with the stock cable, the ear hooks are covered in pre-formed plastic that isn't too stiff but allows reasonably comfortable placement.
The controls can address volume and play/pause (and answer/hang up) so you don't always have to reach for the attached device. The boom microphone connects with a two-pin connector. If you have another boom microphone cable that connects with an MMCX or other connector, this microphone won't be interchangeable. For example, my Kinera boom microphone cable is a two-pin cable, but the boom itself connects with a pin that looks more like MMCX. To be honest, I'm not sure that boom microphone cables are common enough that having them be interchangeable is even a real consideration. It's a tiny niche within a tiny niche for sure.
Sound
You already know that I bought the Halcyon because of the MEMS drivers. I have a few pairs of true wireless earphones (two from Creative) that have xMEMS drivers, so I'm aware how those drivers handle high frequencies with a good level of detail and clarity. I wanted that in a wired experience that I could use for more analytical and/or professional listening scenarios. The earphones I felt were the best competitors in my collection are the aforementioned Raptgo Hook-X. The Hook-X have a planar driver for low-end to midrange frequencies and a piezo-electric driver for the highest frequencies. The bass is fast due to the planar driver, and the highs are bright thanks to the piezo-electric driver. Like the Halcyon, the Hook-X stock cable also has modular connectors, but that cable is very thick and less supple and produces more noise in use.
I was surprised that using the same source that I needed to turn up the volume to get similar loudness on the Halcyon as on the Hook-X. I would have expected the planar drivers to need more volume. I was also surprised that in the end, I felt the Hook-X trounced the Halcyon in almost every category. The Hook-X had more powerful bass, richer midrange, and brighter highs. Detail in pianos and vocals especially stood out on the Hook-X. If I listened to the Halcyon in comparison to other normal hybrid IEMs like my trusty old LZ A5, I preferred the Halcyon. But against the Hook-X, the Halcyon fell flat. I mean literally flat; it did not sound as vibrant and lush as the Hook-X. Drums sounded more real, keyboards had more depth, everything just sounded better. I took me spending another $200 on the Halcyon to really appreciate what I had in the Hook-X because I have to admit I rarely listened to the Hook-X because they're so big and the cable is so annoying and I have more MMCX cables than two-pin so addressing that problem meant spending more money on the Hook-X and I just didn't want to.
Conclusion
In a vacuum or against cheaper IEMs, the Halcyon have lovely highs and a spacey midrange and nice detail. They aren't bass heavy and will likely appeal to listeners who prefer their sound signature on the flatter side (from a frequency response perspective). As an entry point to higher priced novelty IEMs, these could work. But if you love bass, I'd stay away from these. Planars are known for having fast bass without necessarily being bass monsters, but the Hook-X make the Halcyon sound like they're not even trying on the low-end.
Buy these because you're a collector of weird IEMs like me or buy them because perhaps you have the Hook-X and find them to be too bassy or you're looking to upgrade from an older pair of single driver or dynamic/BA driver IEMs. Do not buy them expecting the best listening experience in this price range across the frequency spectrum.
Note: these are not affiliate links and I do not have ties to either company.
To buy from Kiwi Ears:
Kiwi Ears
To buy from Linsoul Audio:
https://www.linsoul.com/products/kiwi-ears-halcyon
YouTube review:
Member discussion: