FiiO FX17 1 Dynamic, 4 BA, 8 Electrostatic Driver IEMs

The FiiO FX17 is FiiO’s flagship in-ear monitor, distilled from 18 years of acoustic experience. Each earpiece holds 13 drivers: a 10mm lithium-magnesium alloy dynamic driver, four custom Knowles balanced armatures and eight Sonion electrostatic drivers, joined by an electronic and physical five-way crossover, FiiO’s S.Turbo bass design and a tuned rear cavity, in shells milled from pure titanium. A gold, silver and copper cable with three twist-lock plugs (3.5mm, 4.4mm and a USB-C DAC) and 22 pairs of ear tips are included, and every pair carries a serial-numbered nameplate. It is Hi-Res Audio certified and won a VGP 2025 Summer award.

1 dynamic, 4 balanced armature, 8 electrostatic

A precisely tuned five-way crossover balances the energy between the 13 drivers per side so each works at its best, for a grander soundstage and a more natural sound.

Eight electrostatic drivers

Electrostatic drivers extend easily to 50kHz and add a sense of air and a grander soundstage, but their sensitivity is only about 99dB/mW against the 110dB/mW typical of balanced armature and dynamic drivers, so the louder low frequencies can mask them. The FX17 therefore uses eight Sonion electrostatics per side, with their own voltage amplifier, to raise their level so they are clearly heard as they handle everything above 6kHz, rather than being there for show.

Four custom Knowles balanced armatures

Two Knowles composite units, each split into a mid and a mid-high section, cover the mids and highs, for denser mids, a more transparent sound and a seamless hand-over to the electrostatics. For flagship vocals, FiiO and Knowles developed a midrange-enhanced armature with acoustic vents in its rear cavity, giving it more sound energy for lush, mellow vocals that put the singer right beside you.

Lithium-magnesium dynamic driver

Lithium-magnesium alloy is light and rigid, with a density of just 1.6g/cm³, making it an ideal diaphragm material second only to beryllium. Its high internal damping greatly reduces resonance and distortion when reproducing fast high-frequency signals, keeping distortion to 0.2% or less for a truly clean sound.

S.Turbo bass and a tuned rear cavity

FiiO’s patented S.Turbo design (patent ZL2018211416279), inspired by supercar turbos, guides sound through a turbo-shaped structure for robust, deep bass while filtering excess mids and highs from the dynamic driver for a smooth transition. Behind the driver, vents just 0.2mm across control the airflow and balance the air damping between front and rear cavities, improving the driver’s Q factor and movement, extending the bass and making the mids clearer.

An electronic and physical five-way crossover

As FiiO’s engineers explain: the FX15’s switch for its electrostatics proved they are not decoration but essential to a wide treble range. The FX17 raises the count to eight per side, covering everything above 6kHz and reducing the power they need, and uses an electronic and physical dual-system five-way crossover for precise control: a smooth frequency response, a flat impedance curve for wide compatibility, and balanced energy and smooth transitions at both low and high volumes.

Pure titanium, two finishes

The classic, naturally curved shell is high-density, high-strength titanium, milled from a single block, hand-polished and hardened with vapour deposition for a lustrous finish. Choose Titanium, with a matte, sandblasted texture that resists fingerprints and scratches, or Silver, with a smooth mirror finish.

A flagship “comfort zone”

• 10° nozzle: after user feedback and research, the nozzle angle is raised 10° on the Y-axis (same length), for a more comfortable, stable fit.
• Snug fit: a more three-dimensional back shell with a 1.4mm ear-conforming ridge in the concha, refined over hundreds of tests.
• Less pressure: about 1mm thinner where it meets the fold of your ear, so it feels as if nothing is there.

Gold, silver and copper cable, three plugs

The cable has 8 strands, 360 wires in all, mixing gold, silver and copper, each forged at over 1,000° and refined a second time into monocrystals to remove impurities and reduce loss, combining the strengths of each metal. Expanded MMCX connectors attach it, and twist-lock plugs swap between 3.5mm, 4.4mm (fitted) and USB-C. The USB-C plug has its own DSP and DAC for up to 32-bit/384kHz PCM with balanced output, and an 8-band PEQ you can set, save and share in the FiiO Control app (Android) or FiiO’s web tool.

Serial-numbered, with 22 pairs of tips

Each FX17 comes with an exclusive engraved, serial-numbered nameplate, and 22 pairs of ear tips, including FiiO’s HS18 and HS20 liquid silicone tips and SpinFit.

Good to know

• The USB-C plug doesn’t support UAC 1.0, so it won’t work with Xbox, Switch or PlayStation consoles; use the 3.5mm or 4.4mm plug with those. App PEQ is Android only (the web tool works on any computer).
• The 22 pairs of tips include foam, bass and balanced (M fitted) tips as well as HS18, HS20 and SpinFit; see the box list.
• For FiiO’s first electrostatic IEM, with a switch to compare, see the FiiO FX15.