64 Audio U4s Universal IEM Earphones

64 Audio U4s Universal IEM Earphones

View cart

Key info

  • The in-ear monitors boast a quad-driver design with a fully tubeless configuration.
  • Thanks to the Tia tubeless design, they effectively reduce resonance, resulting in a transparent and lifelike sound signature.
  • The Apex system plays a crucial role in reducing listener fatigue by releasing sealed air pressure from the ear canal.
  • Achieving sound consistency, the Linear Impedance Design (LID) ensures reliable audio quality, regardless of the audio source.
  • With the incorporation of an Electrical Low-Pass Filter, unwanted frequencies are eliminated, leading to lower distortion levels.
  • The 4-way crossover system, featuring 1 tia High, 1 High-Mid, 1 Mid, and 1 Low driver, enhances audio performance.
  • These monitors come with an exclusive black premium detachable silver-plated audio cable for superior connectivity.
  • The m12 apex modules are exclusively available with the U4s, offering further sound customization options.

All specifications

Impedance 11Ω
Frequency response 10hz – 20kHz
Sensitivity 107 dB/mW
Included accessories
What's in the box U4s Universal In-Ear Monitors, 64 Audio Premium Leather Case, TrueFidelity Foam Ear Tips (S,M,L), SpinFit Silicone Ear Tips (S,M,L), Silicone Ear Tips (S,M,L), 3.5mm Black Premium Cable, Apex Modules: m20, m15, mX Cable Clip, Cleaning Tool, Round Sticker

A quad driver hybrid UIEM featuring ground-breaking patented technologies originally developed for our flagship products in order to bring a wider audience closer to their music. U4s explores a bold new color aesthetic for 64 Audio. The Slate Blue shell color was influenced by some of the world’s most beautiful blue- dial timepieces while the unique faceplate pattern is inspired by Muonionalusta meteorite fragments. Both the faceplate and shell’s illuminant properties give it a unique tone in varying lighting conditions.


U4s sounds light on its feet while effortlessly delivering physically engaging sub-bass without bleeding into the mid-bass. Balanced mid frequencies and a pleasant high-mid band respond well to a wide array of music and recording styles at every volume level; present but not fatiguing. The tia high-driver’s open airy quality couples with the extended sound-stage provided by apex for a lifelike sonic experience.

Its ergonomic anodized aluminum shell houses a single dynamic driver, two balanced-armature drivers, and one patented tia driver; all weaved together with our patented Tia, LID, and Apex technology. The four-way crossover is elevated with the use of our proprietary electrical low-pass filter; reducing low- frequency distortion. The assortment of included apex modules and ear tips are an invitation to further shape the sound based on preference and source material while the ultra- low impedance premium silver-plated copper cable ensures unimpeded signal transmission. The dissemination of tia technology within our product range brings that classic 64 Audio sound signature to a new price-point.

Featured Technology


Tubeless In-Ear Audio (tia) is a patented IEM design methodology that aims to reduce unwanted resonance and distortion for a transparent and lifelike sound signature. The tia system is comprised of three major elements: open balanced armature tia drivers, the tia single-bore design, and tia acoustic chambers. U4s features two major elements of the tia system: the tia driver and the tia single-bore design.


Air Pressure Exchange (Apex) is a patented vent that releases air pressure in a sealed ear canal all while retaining standard IEM levels of isolation; enabling musicians and music enthusiasts to listen more comfortably for longer. This venting alleviates listener fatigue and allows for a much more realistic soundstage. Apex comes in three module variations for U4s: mX, m15, and m20. Linear Impedance


Design (LID) is a patented circuit that corrects the non-linear electrical resistance of the multiple driver-sets comprising this 4 driver IEM. Varying source amplifier output impedance in devices like smartphones, body packs, DAC/amps, and DAPs typically results in varying frequency response across them, depending on the increase in resistance. Restoring proper interaction with the source and preserving the desired sound signature enables a consistent reliable sound.

Electrical low pass filter

A crossover circuit replacing traditional acoustic dampers which can introduce unwanted distortion through vibration and air turbulence. Rather than using acoustic dampers to filter unwanted frequencies after the driver produces them the electrical low pass filter lowers distortion by eliminating unwanted frequencies before they reach the driver.

Leave a review