64 Audio U4s | Hybrid Dynamic + BA Universal IEMs
64 Audio U4s front over white background
64 Audio U4s rear over white background
64 Audio U4s shell closeup over white background
64 Audio U4s front from Bloom Audio Gallery
64 Audio U4s front on wood shelf from Bloom Audio Gallery
64 Audio U4s extreme closeup from brand gallery
64 Audio U4s closeup from brand gallery
64 Audio U4s included Apex modules

64 Audio U4s | Hybrid Dynamic + BA Universal IEMs

Regular price$1,099.00


64 Audio U4s logo

64 Audio U4s Delivers Flagship Tech at an Affordable Price

  • Four-driver hybrid IEM delivers classic 64 Audio performance with a new twist
  • The slate blue shell provides a bold, stylish look
  • The Tia treble driver delivers crisp, clear highs with the new dynamic driver providing deep sub-bass
  • Includes Apex modules for varying isolation, silver-plated copper cable, carrying case, and plenty of ear tips

Bloom's Take

The U4s continues in 64A’s tendency of taking a popular custom IEM style & tuning and converting it into a universal fit that audiophiles crave. They renovated the 4-driver hybrid design of the A4s into a universal shell and slapped on their lowest price yet for a UIEM. Overall, the design is like the popular U6t, Nio, and Fourte, features an anodized aluminum shell with dark gray pearl faceplate, and includes standard 64A package and accessories.

Tuning lands in the popular Harman-esque “bass boosted neutral” but is differentiated in the quality of the bass and excellent air and resolution in the upper treble. It also displays strong imaging characteristics with a reasonably wide and three-dimensional soundstage, albeit not expansive. U4s offers a taste of the 64 Audio signature sound, quality, and engineering at a much more affordable price and is poised to become the new king of the $1099 IEM range.

Read our full review here.

Bold New Look and Sound

Its ergonomic, anodized, aluminum shell houses a single dynamic driver, two BA drivers, and one patented tia driver, all weaved together with our patented Tia, LID, and Apex technology. The 4-way crossover is elevated with the use of our proprietary electronic 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 frequency response of U4s follows proven targets for fidelity and preference. It’s powerful, enveloping, and deep while avoiding being muddy. This kind of bass can only be produced by a dynamic driver. U4s comes short of being classified as warm, rather it is like a tight and agile stand-mount speaker with a well-implemented sub. The key is in keeping the low-frequency rise out of the mid-bass.

Mids are revealing and present, contributing greatly to its wide, stereo imaging and separation. U4s’ perfect balance of presence and body lends itself well to every type of music and volume preference.

64 Audio U4s resting on A&K ACRO CA1000T audio player

Tune Your Sound with Apex and Eartips

The included Apex Modules and Eartips each have different sonic characteristics. You can use different combinations to accentuate different aspects of U4s's sound.

mX Module
Widest imaging with a reduction in noise isolation. Sub-bass response is diminished, giving you the ability to attenuate to your preferences based on music type and mix. It is ideally used for recordings that do not capture much sub-bass content while containing a lot of spatial information.

m12 Module
Developed for those who feel the bass drop between m15 and mX is too drastic. Perfect for tracks where the bass is slightly overpowering the rest of the spectrum. Increases mid-range punch (reduction by 1db-4db at 130hz-20hz.)

m20 Module
Greatly increases sub-bass response while keeping the mid-bass clean. Works great for overly bright mixes as it tilts the response towards low end. While
this module shrinks the sound-stage width, it works great for synth-heavy or modern pop music that doesn’t contain much acoustic spatial information. The m20 module also unlocks some of the missing sub information in older rock recordings (increase by 1db-2db at 40hz-20hz.)

Foam Tips
Narrows the mix and shifts HF resonant peak down. More secure fit.

Shifts HF resonant peak up. Best at handling microphonics and occlusion effects. The nozzle is decoupled well from the silicone touching the ear canal.

Wide Nozzle
Staging is less localized with better panning blend. Hits target frequency response curve with m15 module.

64 Audio U4s internal components explosion diagram


  • Transducer Configuration
    • (x1) Dynamic driver (Lows)
    • (x2) Balanced Armature drivers (Low Mids, High Mids)
    • (x1) Tia driver (Highs)
  • Frequency Response: 10Hz – 20kHz
  • Sensitivity: 107 dB/mW @ 1kHz @ 1mW (94mV)
  • Impedance: 11Ω @1kHz
  • Crossover: Integrated 4-way passive crossover
  • Isolation
    • m20 Module: -20dB
    • m15 Module: -15dB
    • m12 Module: -12dB
    • mX Module: -10dB
  • Cable
    • 0.23Ω total impedance
    • 7 x 7 x 4 Multi-twist
    • Silver-plated OCC copper wire
    • 26 AWG
    • 3.5mm termination
  • 64 Audio 1 Year Warranty

In the Box

  • 64 Audio U4s IEMs
  • Leather carrying case
  • TrueFidelity ear tips (S/M/L)
  • Silicone ear tips (S/M/L)
  • SpinFit ear tips
  • Ear tip holder
  • Black premium Silver-plated copper cable with 3.5mm
  • 64 Audio Apex modules (mX, m12, m15, m20)
  • 64 Audio Sticker

64 Audio U4s package and accessories

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

Customer Reviews

Based on 1 review

The main thing I like about these IEMs is the comfort. The nozzle is not too long or wide, like other IEMs in this or higher price ranges. Very non fatiguing. Additionally, the sound is amazing for this price point as well!

The Apex modules are a fantastic idea and very user friendly for someone who does not know how to EQ.

Amazing product, thanks for the giveaway guys!!!

You may also like

Recently viewed