64 Audio A4s
Best custom in-ear monitor for discerning audiophiles and professional stage performers.
The 64 Audio A4s is a sophisticated hybrid custom in-ear monitor (IEM) utilizing a four-driver platform, including a dedicated dynamic low-frequency driver. It integrates 64 Audio's signature Tia technology and LID circuits to ensure consistent frequency response across various audio sources. Designed for both immersive monitoring and critical audiophile listening, the A4s delivers exceptional detail and soundstage clarity. Listeners frequently praise its fantastic sub-bass extension and finely tuned midrange performance. This 2021 release offers superior comfort through Apex and 3Dfit technologies, establishing a high benchmark for fidelity.
$1099.00
More A Series Options
Owner Satisfaction
4.6
/ 5
Category Rank
454
/ 6144
#454 in Headphones
Price vs Category Average
+87%
Above average
Transducer Type
Dynamic & Balanced Armature
/ Dynamic & Balanced Armature
Who it's for
- Critical listeners seeking a balanced and natural sound profile
- Audiophiles prone to ear fatigue during long listening sessions
- Professional musicians needing perfect isolation and a secure fit
Who should skip it
- Impulsive buyers who prioritize quick delivery and resale flexibility
- Budget-conscious buyers avoiding complex, time-consuming custom fitting processes
- Detail-oriented listeners demanding the absolute maximum technical resolution
Performance breakdown
Sub-bass extension
The dedicated dynamic driver delivers deep, authoritative lows with remarkable precision.
Midrange clarity
Vocals and instruments sit perfectly in the mix with exceptional detail.
Source consistency
LID technology ensures the sound profile remains stable across all devices.
Comfort and fit
Apex and 3Dfit technologies allow for fatigue-free listening during long sessions.
Soundstage imaging
Tia technology creates an expansive, open soundstage rarely found in IEMs.
Passive isolation
Effectively blocks external noise while maintaining a comfortable, pressure-free seal.
Key Specs
Transducer Type
Dynamic & Balanced Armature
Transducer Configuration
1 dynamic low, 1 BA low-mid, 1 BA high-mid, 1 tia high
Frequency Response
10Hz – 20kHz
Sensitivity
107 dB/mW (94mV) @ 1kHz
Impedance
11Ω @ 1kHz
Crossover
Integrated 4-way passive crossover
Ear Type
In-Ear-Monitor (IEM)
Release Year
2021
Features
- Hybrid driver configuration for rich sound
- Consistent frequency response with LID technology
- Alleviates ear pressure with Apex technology
- Enhanced clarity with Tia technology
- Custom fit for superior comfort
- Exceptional sub-bass extension
- High-fidelity monitoring experience
- Top-tier build quality
What customers say
Reviewers consistently praise the exceptional comfort and superior sound quality of the 64 Audio A4s. Audio reproduction is natural and articulate, delivering clear vocals and instruments without harshness. The bass response is tight and accurate, offering impact without muddiness. Users note that the Apex technology significantly reduces listening fatigue during extended use. While these monitors represent a premium investment, the consensus is that the professional grade performance and enhanced listening comfort fully justify the value.
Know before you buy
The A4s combines a dynamic driver for deep, impactful low frequencies with three balanced armature drivers to handle the mids and highs. This hybrid design allows the monitor to deliver the punch of a traditional speaker alongside the precision and detail of professional balanced armature technology.
LID (Linear Impedance Design) ensures that the A4s maintains a consistent sound signature regardless of the device you plug it into. Whether you are using a high-end studio interface or a standard portable player, the frequency response remains stable and accurate.
Yes, the A4s features 3Dfit technology for a precise custom fit and Apex technology, which vents ear canal pressure. These features work together to reduce listener fatigue, making them suitable for extended monitoring or long listening sessions.
Tia (Tubeless In-ear Audio) technology removes the need for sound-altering acoustic tubes and dampers. By placing the high-frequency driver directly into the ear canal, it significantly reduces resonance and distortion, resulting in a clearer, more open soundstage.
With an impedance of 11Ω and a sensitivity of 107 dB/mW, the A4s is relatively easy to drive. While a high-quality dedicated amplifier can help extract the best performance, they are efficient enough to work well with most modern portable devices.
Because the A4s is a custom-molded in-ear monitor, it provides excellent passive noise isolation by creating a physical seal within your ear canal. This effectively blocks out ambient noise, allowing you to focus on your audio without needing active noise cancellation.
Still have a question?
Ask Hayley anything about this product before you decide.