64 Audio U4s
Best hybrid monitor for audiophiles seeking a customizable, engaging sound signature.
The 64 Audio U4s is a quad-driver hybrid universal in-ear monitor launched in 2023. It incorporates patented flagship technologies to deliver a versatile sound signature, adjustable from bassy to neutral via included tuning modules. Users benefit from excellent bass texture and deep extension provided by the dynamic driver, complemented by very good treble air for detailed, non-harsh high frequencies. The design emphasizes comfort and durability with a lightweight anodized aluminum shell, offering an engaging audio experience.
$1099.00
Owner Satisfaction
4.6
/ 5
Category Rank
454
/ 6144
#454 in Headphones
Price vs Category Average
+87%
Above average
Drivers
1111
/ tia High Driver, High-Mid Driver, Mid Driver, Dynamic Low Driver
Who it's for
- Audiophiles prone to ear fatigue during long listening sessions
- Listeners seeking a versatile, musical sound for diverse music libraries
- Tinkerers who enjoy fine-tuning their sound signature and isolation levels
Who should skip it
- Budget-conscious buyers looking for entry-level or mid-tier value
- Bass-heads craving the physical slam of dynamic driver sub-bass
- Premium enthusiasts expecting high-end accessories to match the shells
Performance breakdown
Bass Texture
Dynamic driver delivers deep, impactful lows with exceptional physical presence.
Treble Clarity
Tia technology provides detailed, airy highs without any harsh fatigue.
Tuning Versatility
Interchangeable Apex modules allow seamless shifts between neutral and bass-heavy signatures.
Source Consistency
LID technology ensures stable, reliable performance across various audio sources.
Build Ergonomics
Lightweight aluminum shell offers long-term comfort for extended listening sessions.
Soundstage Depth
Wide, immersive staging creates a lifelike and engaging spatial experience.
Key Specs
Drivers
1 tia High Driver, 1 High-Mid Driver, 1 Mid Driver, 1 Dynamic Low Driver
Frequency Response
10Hz - 20kHz
Sensitivity
107 dB/mW @1kHz
Impedance
11 Ω @1kHz
Crossover
Integrated 4-way Passive
Isolation
-20dB, -15dB, -10dB
Cable
Silver Plated OCC Copper Wire, 26 AWG
Connectivity
Wired
Features
- Hybrid driver system with a powerful dynamic driver for impactful bass
- Incorporates patented tia, LID, and Apex technologies for superior sound
- Includes interchangeable APEX modules for customizable bass and treble tuning
- Ergonomic anodized aluminum shell in a striking slate blue finish
- Proprietary electronic low-pass filter reduces distortion for cleaner sound
- LID technology ensures consistent performance across various source devices
- Wide soundstage and lifelike sonic experience
- Designed for audiophiles and musicians seeking a U-shaped sound signature
What customers say
The 64 Audio U4s deliver exceptional comfort perfect for extended listening sessions. Reviewers consistently praise the natural balanced sound signature, which expertly handles diverse music genres. A standout feature is the deep, textured bass that provides satisfying impact without sacrificing clarity. The integrated APEX technology successfully reduces listening fatigue, supporting sustained use. While the initial cost is premium, the superior build quality and professional audio performance establish compelling overall value. Many consider the U4s a reliable choice, successfully balancing critical listening with genuine musical enjoyment.
Know before you buy
The APEX modules allow you to adjust the bass response and soundstage by changing the internal air pressure. Swapping them lets you shift the U4s from a punchy, bass-forward signature to a more neutral, balanced profile depending on your preference.
Thanks to 64 Audio's LID technology, the U4s maintains a consistent sound signature regardless of the source device. While they are easy to drive, using a high-quality DAC or amplifier will help you extract the best detail and clarity from the hybrid driver system.
The U4s features a versatile U-shaped sound signature. It delivers deep, textured bass from the dynamic driver, clear mids, and detailed, non-fatiguing highs, making it well-suited for both critical listening and casual enjoyment.
The U4s provides excellent passive isolation, ranging from -10dB to -20dB depending on the APEX module installed. This design effectively blocks out ambient noise, making them suitable for use in busy environments or during travel.
Yes, the shell is crafted from lightweight anodized aluminum and features an ergonomic shape designed for extended wear. The combination of the lightweight material and the pressure-relieving APEX technology helps prevent ear fatigue during long sessions.
The patented tia driver is a tubeless design that reduces resonance and distortion. By removing the sound tube, it allows for a more open, airy, and lifelike high-frequency response compared to traditional balanced armature drivers.
Still have a question?
Ask Hayley anything about this product before you decide.