FiiO FA19 New Flagship 10 Knowles BA Driver IEMs

The FiiO FA19 is FiiO’s flagship all-balanced-armature in-ear monitor, three years in the making, with ten Knowles drivers per ear. FiiO worked closely with Knowles to create a custom enhanced-bass balanced armature for deep low frequencies uncommon in multi-BA IEMs, and to optimise the mid and treble drivers for detail with smoothness, then tuned the whole response for a coherent, resolving sound. A Monitor/HiFi switch, a pure silver cable with swappable plugs and Hi-Res certification complete it. Its awards include an EHA 2024 Gold Award and VGP Life Style awards in 2024 and 2025.

Ten Knowles balanced armatures

Each earpiece holds four custom Knowles bass drivers, two Knowles ED mid drivers and four Knowles SWFK treble drivers, a choice based on both science and listening tests. More drivers increase the energy density in each frequency range, reproducing more detail, especially in dynamic passages where the sound must not be compressed, and give the engineers ample reserves to reach their tuning goals. A physical plus electronic three-way crossover divides the frequency range accurately between the drivers, for a clear, reference-monitor-like sound with real impact.

Custom enhanced-bass drivers and negative-feedback bass

FiiO and Knowles improved the airflow of the custom bass driver to raise its energy, and four of them per channel give robust, impactful bass. The 3D-printed shell guides low-frequency sound waves into the rear cavity, lowering its resonant frequency: a negative-feedback bass enhancement system that reaches unusually deep for an IEM of this kind.

A mid-frequency notch filter

Knowles ED mid drivers are prized for their resolution but can sound sibilant if not implemented well. FiiO’s engineers placed a notch filter at the base of the two mid drivers: a resonant cavity that absorbs sound energy near its own frequency, filtering out the mid driver’s 8kHz peak. That reduces the overlap with the treble drivers to eliminate sibilance, moves the mid-to-treble crossover point to 3.5kHz for a clean hand-over, and raises the level between 1kHz and 3kHz to avoid a hole in the mids, for lusher, more realistic vocals.

Rubycon crossover capacitors

Audiophile-grade Rubycon film capacitors, with tolerances below 0.1% (against about 1% for typical crossover parts), set the crossover points precisely and give better treble resolution than ordinary ceramic capacitors, without losing tonal finesse.

S.Turbo and a DLP 3D-printed shell

FiiO’s patented S.Turbo turbine-shaped acoustic design (patent ZL2018211416279) extends the bass tube so it filters out high frequencies from the bass drivers, for a smooth, clean transition from bass to mids. The shell is DLP 3D-printed to a precision of 0.0375mm in durable photosensitive resin, which makes the negative-feedback bass system possible and protects the drivers.

One switch, two sounds

A switch on the back of each earpiece chooses the mode on the fly. Monitor mode gives clean, detailed sound, especially in the treble, making the FA19 an excellent tool for audio production; HiFi mode adds energy to the mids and bass, with particular attention to bass impact and quantity, for pleasant hi-fi listening.

A pure silver cable with swappable plugs

The cable, the same as FiiO’s LC-RD Pro 2022, has 8 strands of 28 high-purity silver wires (224 in all), each individually insulated and Litz-braided, in a clear, eco-friendly TPU sheath that resists yellowing and stiffening in the cold. It connects by expanded MMCX, and straight twist-lock plugs swap between 3.5mm and 4.4mm balanced (plug design licensed from FABRILOUS; FiiO ships either the newer or older plug, which differ only in construction).

Tuned under the supervision of FiiO’s acoustic experts, the FA19 is certified Hi-Res Audio by the Japan Audio Society and the Consumer Electronics Association.

Good to know

• At 10Ω and 106dB/mW the FA19 is easy to drive; a quiet source with low output impedance suits it best.
• In the box: FA19, silver cable with 3.5mm and 4.4mm plugs, HB5 case, seven sets of eartips (foam, bass, balanced, dual-flange, vocal, SpinFit and HS18), magnetic cord clip, cleaning brush, MMCX tool and quick start guide.