FiiO FH5S

The FiiO FH5S takes a radically different approach with its 2DD+2BA architecture and semi-open design—two unusual features that completely transform its sonic character. Hi-Res Audio certified and equipped with a tri-band customization system, the FH5S aims to democratize access to reference-quality sound reproduction without compromising versatility.

Revolutionary Acoustic Architecture

The FH5S breaks away from traditional hybrid IEM conventions by adopting a particularly sophisticated 2DD+2BA configuration. Unlike its predecessor, which used a balanced armature for the mids, this model entrusts this crucial task to a specially designed 6mm dynamic driver. This approach enables a more natural and coherent transition between bass and mids, eliminating the frequency discontinuities sometimes noticeable in classic hybrid setups.

The main 12mm driver, featuring a beryllium-plated diaphragm and N52 magnets generating a magnetic force of 1.5 Tesla, forms the heart of this architecture. This setup delivers bass that is both deep and perfectly controlled, with dynamics and precision that sources describe as “reference-level.” The geometry of the rigid yet flexible polyurethane surround optimizes acoustic coupling while minimizing distortion.

For high frequencies, FiiO uses Knowles TWFK-30017 balanced armatures, positioned as close as possible to the ear canal to minimize high-frequency loss. This dual configuration allows for remarkable extension up to 40 kHz while preserving the finesse and detail of treble instruments.

Semi-Open Design and Premium Construction

The choice of a semi-open design is one of the FH5S’s boldest innovations. Unlike traditionally closed IEMs, this approach incorporates calibrated vents that balance internal acoustic pressure. The result is a remarkably wide and natural soundstage, more reminiscent of listening to speakers than traditional earphones.

Construction utilizes FiiO’s TRISHELL technology, which layers three CNC-machined aluminum-magnesium alloy shells. This sandwich architecture, fixed at three strategic points, effectively eliminates unwanted resonances and shell distortions that typically degrade sound reproduction. The final result weighs only 8.8 grams per earpiece, demonstrating the efficiency of this construction approach.

The external mesh guides blend seamlessly into the design of the faceplates, creating a visually coherent whole while optimizing acoustic flow. This attention to aesthetic detail reflects FiiO’s maturity in designing high-end IEMs.

Advanced Sound Customization System

The FH5S inherits the switch system initially developed for the FA9, offering eight distinct sound signatures. Three independent switches allow separate adjustment of bass, mids, and treble, creating rare versatility in this product category. This approach goes beyond simple equalization by acting directly on the acoustic crossover.

The adjustments do not produce drastic changes but allow for precise fine-tuning according to musical preferences and source characteristics. This modularity is especially appreciated for adapting the sound signature to different music genres or correcting imbalances in certain recordings.

Implementing this system requires complex acoustic engineering to maintain tonal coherence in all configurations. FiiO has clearly mastered this technology, as confirmed by positive user feedback on the smoothness of transitions between settings.

Optimized Comfort and Ergonomics

The over-ear design of the FH5S prioritizes stability and comfort during long listening sessions. The semi-custom shape naturally adapts to the ear’s contours, while the reduced weight prevents fatigue. Passive isolation, though less than with a closed design, remains sufficient for most listening environments.

The wealth of included eartips (13 pairs of various types) allows for precise adjustment according to individual ear shape and sound preferences. This variety includes bi-flange, vocal, bass, balanced, and foam tips, covering all needs for acoustic adaptation and comfort.

The over-ear cable features colored markers (blue/red) for easy channel identification—a practical detail appreciated during repeated use. The flexible silver-plated monocrystalline copper cable also contributes to overall comfort without causing microphonic effects.

Versatile Connectivity and Ecosystem

The interchangeable connector system in 316L stainless steel is one of the FH5S’s major practical advantages. The three available formats (2.5mm, 3.5mm, and 4.4mm) cover all modern sources, from smartphones to audiophile DAPs and dedicated headphone amplifiers.

The twist-lock mechanism ensures a reliable connection while maintaining ease of swapping. This versatility eliminates the need for additional cable investments and optimizes compatibility as the user’s audio ecosystem evolves.

The main cable, 120cm in length, uses a Litz architecture in silver-plated monocrystalline copper to preserve sonic transparency. The eco-friendly TPU sheath reflects FiiO’s growing environmental concerns, with no compromise on electrical performance.

Major Evolution Compared to the FH5

The transition from the FH5 to the FH5S is much more than a simple incremental update. The increase in main driver size from 10mm to 12mm significantly improves dynamics and bass extension. More fundamentally, replacing the balanced armature for the mids with a dedicated dynamic driver completely transforms the sound character.

This new architecture eliminates the tonal discontinuities sometimes noticeable between bass and mids, creating superior fluidity and naturalness. The addition of the switch system, absent from the original FH5, multiplies the possibilities for adaptation according to taste and source.

Some reviewers even claim that the FH5S outperforms the FH7, a model positioned higher in the FiiO lineup. This flattering comparison attests to the effectiveness of the technical choices made for this evolution.

Technical Specifications

Architecture and Design

• 3-way in-ear monitors with 2 dynamic drivers and 1 balanced armature
• Semi-open design for a wide soundstage and extended comfort
• Over-ear cable guide for optimal fit
• CNC-machined aluminum-magnesium alloy shells, robust and lightweight
• TRISHELL sandwich-structure back with 3-point mounting to reduce resonance and distortion
• Audio filter adjustment via 3 switches for bass, midrange, and treble
• Detachable MMCX connectors, left/right marked for ease of use
• Hi-Res Audio certification

Drivers

• Bass: 12 mm dynamic driver with beryllium-plated diaphragm, PU surround, and N52 magnets
  • Magnetic force: 1.5 Tesla
• Midrange: 6 mm dynamic driver, also beryllium-plated
• Treble: Knowles TWFK-30017 balanced armature driver, positioned close to the ear to reduce high-frequency loss

Electroacoustic Performance

• Frequency response: 10 Hz – 40 kHz
• Impedance: 40 Ω (at 1 kHz)
• Sensitivity: 106 dB / mW
• Maximum input power: 100 mW

Cabling and Connectivity

• 120 cm detachable cable made of single-crystal copper plated with silver
  • Litz-style braiding
  • Eco-friendly transparent TPU sheath
• 3.5 mm mini-jack to MMCX connector
• 3 types of interchangeable plugs in 316L stainless steel: 2.5 mm, 3.5 mm, 4.4 mm
  • Twist-lock system

Included Accessories

• HB5 carrying case
• 13 pairs of ear tips in various sizes and shapes: bi-flange, vocal, bass, balanced, foam
• Cleaning tool
• MMCX assist tool
• User manual
• Accessory storage pouches

General Information

• Weight per earphone: approximately 8.8 g
• Type: over-ear (in-ear monitors with cable guide)