Description
The 64 Audio U4s is a quad-driver hybrid universal in-ear monitor for musicians and listeners seeking flagship 64 Audio technology at an accessible price point. Its ergonomic anodized aluminum shell — finished in Slate Blue with a Muonionalusta-meteorite-inspired faceplate — houses one dynamic low driver, two balanced armatures, and one patented tia high driver, managed by an integrated 4-way passive crossover.
Three patented technologies define the U4s. Tubeless In-Ear Audio (tia) reduces unwanted resonance for a transparent, lifelike signature. Air Pressure Exchange (Apex) vents ear-canal pressure while retaining isolation, supporting more comfortable listening over longer sessions — and interchangeable Apex modules with isolation options of -10 dB, -15 dB, and -20 dB let you tune comfort and isolation to your environment. Linear Impedance Design (LID) corrects the non-linear electrical resistance of the driver sets, helping deliver a consistent frequency response from sources with varying output impedance, from smartphone outputs to DAC/amps.
The included ultra-low-impedance (0.23 Ω) silver-plated OCC copper cable terminated in 3.5mm keeps signal transmission unimpeded, while TrueFidelity foam and SpinFit silicone ear tips in three sizes help you find a secure fit. A premium leather case protects everything between gigs. Designed, assembled, and QC'd in the United States.
Specifications
| Driver configuration | 1 tia High Driver, 1 High-Mid Driver, 1 Mid Driver, 1 Dynamic Low Driver |
| Frequency response | 10 Hz – 20 kHz |
| Sensitivity | 107 dB/mW @1kHz |
| Impedance | 11 Ω @1kHz |
| Crossover | Integrated 4-way passive crossover with proprietary electrical low-pass filter |
| Apex isolation | -20 dB, -15 dB, -10 dB (via interchangeable Apex modules) |
| Cable | 3.5mm Black Premium Cable, 0.23 Ω total impedance, 7x7x4 Multi-Twist silver-plated OCC copper wire, 26 AWG |
| Shell | Ergonomic anodized aluminum, Slate Blue with meteorite-pattern faceplate |
| Included accessories | Premium leather case, TrueFidelity foam tips (S/M/L), SpinFit silicone tips (S/M/L), silicone tips (S/M/L), Apex modules (m20, m15, mX), cable clip, cleaning tool |
