FiiO FT15 – Flagship open-back planar with a diamond-coated diaphragm

The FT15 is FiiO's flagship open-back planar magnetic headphone, built around a 101 mm driver with 6,443.5 mm² of effective radiating area. Its 800 nm diaphragm is 86.7% thinner than the previous generation and carries a full-surface diamond coating, so it stays rigid without gaining mass and keeps its response clean out to 40 kHz. North American FAS-grade black walnut earcups and a carbon fibre headband hold the weight to 425 g.

Key Features

• 101 mm planar driver: 6,443.5 mm² of effective radiating area for a wide, open stage.
• 800 nm diamond-coated diaphragm: 86.7% thinner than the previous generation, with a full-surface diamond coating applied by vapour deposition to reduce high-frequency breakup.
• Patented uniform magnetic field: Custom contoured high-strength magnets drive the diaphragm evenly and cut vibrational distortion at the source.
• 28 nm electroplated voice coil: Chip-grade process with a silver-aluminium alloy coating for a structurally stable coil.
• Easy to drive: 95 dB/mW sensitivity and 24 Ω impedance, so a USB dongle can carry it.
• 425 g with carbon fibre headband: Light for a full-size planar, with pressure spread for long sessions.
• Black walnut earcups: North American FAS-grade walnut, so every pair has its own grain.
• Cryo-treated 6N copper cable: 99.99998% monocrystalline copper, treated 100+ hours at −192 °C, terminated in 4.4 mm balanced.
• Two sets of earpads: Suede pads fitted from the box for warmth and bass weight, protein leather pads for extra treble resolution.
• Hi-Res Audio certified: Certified by the Japan Audio Society.

Customer Benefits

Big planars usually demand a big amplifier. The FT15 does not: 24 Ω and 95 dB/mW mean a dongle or a modest desktop amp already gets it to volume, and the 101 mm driver still gives you the scale you buy a full-size planar for. The two pad sets let you tune the balance yourself, the 4.4 mm balanced cable ships with 6.35 mm and XLR-4 adapters so it fits whatever output you already own, and 425 g on a carbon fibre headband keeps a long evening comfortable.

Quick Specs

• Type: Full-size open-back planar magnetic
• Driver: 101 mm proprietary planar, 6,443.5 mm² radiating area
• Frequency response: 7 Hz to 40 kHz
• Impedance: 24 Ω at 1 kHz
• Sensitivity: 95 dB/mW (111 dB/Vrms) at 1 kHz
• Weight: 425 g without cable
• Clamping force: 3.8 N ±0.3 N
• Cable: 1.5 m, 6N monocrystalline copper, dual 3.5 mm TS to 4.4 mm balanced

What's in the Box

• FT15 headphones
• 4.4 mm balanced headphone cable
• XLR-4 (male) to 4.4 mm (female) balanced adapter
• 4.4 mm (female) to 6.35 mm (male) adapter
• Suede earpads (pre-installed)
• Protein leather earpads
• Fabric storage case
• Quick start guide

Ideal For

Home listening on a desktop or valve amp, balanced 4.4 mm sources, and listeners who want flagship planar scale without a power-hungry load.

Pros & Cons

✅ Pros:

• 101 mm driver with an 800 nm diamond-coated diaphragm
• 24 Ω and 95 dB/mW, so it runs from a dongle
• Two pad sets included for two voicings
• 4.4 mm balanced cable plus 6.35 mm and XLR-4 adapters
• Walnut and carbon fibre build at 425 g

⚠ Cons:

• Open-back design leaks sound both ways, so it is a room headphone, not an office or commuting one
• No 3.5 mm single-ended cable in the box, so a 3.5 mm source needs an adapter you supply

If you want the scale of a 101 mm planar without building an amplifier chain around it, the FT15 is the easiest flagship in its class to live with.