Description
Enjoy a ground-breaking performance with the 64Audio U4s. This hybrid quad-driver IEM features the same patented audio technologies like tia and Apex Core developed for flagships at an irresistible price point.

Created For You
Experience a light and engaging sound with impressive sub-bass without compromising mid-bass clarity with the 64Audio U4s. Its balanced mid frequencies and pleasant high-mid band perform well with various music genres and recording styles, without causing listener fatigue. The tia high-drive r's airy quality and the extended sound-stage from the Apex Core technology provide a lifelike and immersive listening experience.

Tuned For You
The 64Audio U4s achieves a powerful, deep, and enveloping sound without sacrificing clarity, thanks to its dynamic driver. Its frequency response follows proven targets for fidelity and preference, avoiding muddiness and excessive mid-bass. The mids are revealing and contribute to its wide stereo imaging, while the high frequencies strike a balance between neutrality and detail, offering the perfect blend of presence and body.
Beautiful Blue
The 64Audio U4s features a Slate Blue shell with a unique faceplate inspired by Muonionalusta meteorite fragments. The colour was influenced by beautiful blue-dial timepieces and the illuminant properties of the shell and faceplate give it a distinct look in different lighting conditions.

Listen with the Best
The U4s boasts an ergonomic anodised aluminium shell that contains a single dynamic driver, two balanced-armature drivers and one patented tia driver. Its four-way crossover is further enhanced by the proprietary electronic low-pass filter, reducing low-frequency distortion. The ultra-low impedance premium silver-plated copper cable guarantees uninterrupted signal transmission.
Put a Lid on It
The different source amplifier output impedances of smartphones, DAC/Amps, Hi-Res Audio Players and more, can cause the frequency response to varying across devices based on the increase in resistance. A patented Linear Impedance Design (LID) circuit corrects the non-linear electrical resistance of the multiple drivers sets to restore proper interaction with the source device. It preserves the desired sound signature while staying constant and reliable.
Enjoy Your Music with tia
The U4s’ patented Tubeless In-Ear Audio (tia) system reduces unwanted resonance and distortion for a transparent and lifelike sound. This is achieved by allowing the Dynamic Driver and tia Balanced Armature Drivers to radiate freely in the single large tia bore with no obstructions in front of the drivers. It features special acoustic chambers instead of tubes that constrict the sound of the drivers.
No Dampers, It’s Electrifying!
Old technologies like acoustic dampers merely blocked frequencies from reaching the ear instead of preventing it from reaching the drivers. This introduced distortion due to the vibration and air movement at higher volumes. The 64Audio U4s uses the same electrical low pass filter, developed for the outstanding U18s, which reduces distortion while eliminating unwanted target frequencies before they reach the driver.
Apex Core Technology Looks as Good as it Sounds
The Air Pressure Exchange (Apex) Core allows a seamless airflow to the solid anodised aluminium shell that uses a perforated grill on the elegant faceplate to prevent the obstruction of air for effortless reproduction of music and minimal physical fatigue. This patented vent releases air pressure for better comfort and lesser fatigue while enhancing noise isolation. This technology comes in four module variations: mX, m12, m15 and m20.

Know Your Modules
- mX: Provides wide imaging with reduced noise isolation and a decreased sub-bass response. Perfect with recordings that have more spatial information and less sub-bass content. The reduction (by 1db-10db at 350Hz-20Hz) in the sub-bass response creates a slight emphasis on the high-frequency band.
- m12: Developed to address concerns from users who found the bass drop between m15 and mX to be too significant by reducing bass by 1dB-4dB at 130Hz-20Hz. Ideal for tracks where the bass is slightly overpowering other frequencies and can provide increased mid-range punch.
- m15: Enhances the audio staging by creating a natural and less localised sound. It also provides a better panning blend, resulting in a more cohesive and immersive listening experience and an accurate target frequency response curve.
- m20: Increases sub-bass response while keeping the mid-bass clean, making it ideal for bright mixes and modern pop music. While the sound-stage width is reduced, it works well for synth-heavy tracks and unlocks missing sub-information in older rock recordings.

TRANSDUCER TYPE/COUNT
2 balanced armature drivers, 1 tia driver, and 1 dynamic driver
TRANSDUCER CONFIGURATION 1 dynamic low, 1 BA low-mid, 1 BA high-mid, 1 tia high
FREQUENCY RESPONSE 10Hz – 20kHz
SENSITIVITY
107 dB/mW @ 1kHz @ 1mW (94mV)
IMPEDANCE 11Ω @1kHz
CROSSOVER
Integrated 4-way passive crossover
ISOLATION
-20dB w/ m20 module
-15dB w/ m15 module
-12dB w/ m12 module
-10dB w/ mX module
CABLE
0.23 Ohms total impedance
7 x 7 x 4 Multi-twist
Silver-plated OCC copper wire 26 AW
In The Box
•U4s Universal In-Ear Monitors
• 64 Audio Premium Leather Case
• TrueFidelity Foam Eartips (S,M,L)
• SpinFit Silicone Eartips (S,M,L)
• Silicone Eartips (S,M,L)
• 3.5mm Black Premium Cable
• Cable Clip
• Cleaning Tool
• Apex Modules: m20, m15, *m12, mX
• Round Sticker
Warranty Period: 2 Years from the date of Invoice
Covered: Manufacturing Defects Only
Warranty Form: https://www.theaudiostore.in/pages/warranty-claim-form
64 Audio is a leading manufacturer of high-end in-ear monitors for audiophiles, musicians, and professionals. With a focus on innovation and craftsmanship, 64 Audio delivers unparalleled sound quality and precision. Discover their range of custom and universal-fit models at The Audio Store and experience audio like never before. Shop now!
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Let customers speak for us
from 6945 reviews
packing, The IEM’s delivery all amazing. loved it
Thank you Sir/ma’am for this product worth every penny on ears
Great sound quality for the price. The bass is punchy, vocals are clear, and overall audio feels well-balanced. The different sound modes in the app make listening more fun and customizable. Definitely a solid Type-C IEM option.
Pretty good and compact Dac at this price range.
Using the KEFINE Delci AE 4.4mm primarily for competitive FPS gaming, and it’s honestly outstanding for the price. The imaging is excellent — footsteps are easy to pinpoint, directional cues are very clear, and separation in busy scenes is impressive. This makes a real difference in games like PUBG, Valorant, and CS where positional audio matters.
The tuning feels very well-suited for competitive play: clean mids, controlled bass that doesn’t mask details, and crisp highs that help with awareness without being overwhelming. Paired with a balanced source, it has plenty of headroom and sounds very resolving.
For under $100, it’s hard to think of anything that comes close in terms of imaging and competitive performance. I’ve had no real complaints using it for long gaming sessions, and it delivers exactly what you’d want from a serious FPS-focused IEM.
If your priority is competitive gaming and positional accuracy, the Delci AE is an easy recommendation in this price range.
Good Sound Clear Trebles And solid build qualityfor the budget.
These are my 3rd pair of IEMs and can't say anything bad about these!
Excellent smooth and balanced sound stage with clear vocals, totally worth it!
Bought these as an upgrade to my iem stock cables, totally worth it!
Excellent build quality and improved sound stage 💯
Writing this review after almost two months of use, I can confidently say this IEM is amazing for the price. It arrived within three days and in perfect condition. Describing the product in such a short review is difficult, but in one line, the sound quality is impressive, though it may vary based on personal taste.
The bass is controlled (not boomy), with good clarity and a balanced V-shaped sound signature. It feels like I am in a mini theater :). I really like this IEM—my IEM journey starts here.
Kefine klean is one of the best iem is this price ❤️❤️💕
IEM reviewer eargasmic3060 recommended me as per my taste. I had asked for an IEM with ideal bass, neutral mids, decent detail on highs without sibilance. This IEM checked all the boxes. Very highly recommended for long non tiring listening. You shall customise your listening by tip rolling. Additionally, you shall choose nozzles based on your preference. This provides huge versatility. Overall, I'm very happy with the purchase. You shall go for it if you prefer neutral warm sound with decent highs without sibilance.
Awesome 👍😎
Awesome 👍😎
Liked the sound quality and loved the build quality
Moondrop audio devices consistently deliver their best performance when tuned to Moondrop’s own target response. If you purchase a Moondrop product, it is recommended to apply the same VDSF target EQ curve to achieve optimal sound quality and full performance potential.
First of all this is my 1st IEM, (3.5 mm)❤️❤️
After received this IEM , I feel like wow I got my budget iem its a great deal because its sound quality like amazing, I hearing every note, and when I first wore this almost surrounding noise became low and it fits perfect in ears, cable is looks good and mic quality is really good hears clearly without any disturbance.
I really satisfied with this IEM










