How We Research
We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-26 · 7 min read · Independent comparison
• FiiO FD15 — biggest strength: a 13.8 mm dynamic driver with a magnesium-aluminum dome and DLC suspension, plus the F.T.B.S "Tesla Valve" low-frequency loading patent and a W-shaped suspension that FiiO says lifts effective vibrating area by 30%. It's a wired, stainless-steel-shell IEM aimed squarely at sound-quality-first listeners.
• FiiO FD15 — biggest trade-off: it's fully wired, has no noise cancelling and no battery, so it depends entirely on whatever you plug its 3.5 mm jack into.
• Technics Reference Class Hi-Fi — biggest strength: a wireless feature stack — Dolby Atmos with head tracking, adaptive noise cancelling, 3-device multipoint, up to 10 hours of playback (28 with the case) and wireless charging.
• Technics Reference Class Hi-Fi — biggest trade-off: it's a plastic-bodied, battery-dependent earbud, so long-term listening is capped by charge cycles rather than by a cable.
• Who each is for: pick the FiiO FD15 for critical wired listening at a desk or with a DAC; pick the Technics for commuting, calls, travel and movies on the move.
The FD15 is the pick for someone who treats the earphone as the main event. Its 13.8 mm dynamic driver uses a magnesium-aluminum alloy dome with a DLC suspension — a materials combination FiiO frames as headphone-grade — and the company claims it pays off in high-frequency extension and resolution, with a bright, transparent character. In my reading of that spec, this is a tuning aimed at detail and air rather than a thick, warm blanket of sound. The W-shaped independent suspension design is the other half of the story: FiiO states it increases the effective vibrating area by 30% compared with conventional diaphragms of the same size. A larger effective area moving more air generally means more stored acoustic energy, which is the engineering logic behind the "dense and grounded" bass FiiO describes.
Who should buy it: listeners with a decent source — a dongle DAC, a DAP, a desktop amp — who want a stainless-steel-shelled, wired IEM and care more about driver engineering and cable quality than about convenience features. Who should skip it: anyone who wants to walk around untethered, take calls hands-free, or block out a train carriage. The FD15 has no noise cancelling, no battery, no Bluetooth and no microphone beyond its remote control — it's a 32-ohm wired earphone with a 3.5 mm jack, and that's the whole point.
Technics Reference Class Hi-Fi: Who It's For
The Technics Reference Class Hi-Fi (model EAH-AZ100-N) is the opposite philosophy executed well. It's a true-wireless earbud with a planar magnetic driver rated from 20Hz to 40kHz, Bluetooth 5.3, touch controls and adaptive noise cancelling that Technics says adjusts automatically to your surroundings. The magnetic fluid driver design is claimed to deliver low distortion, accurate bass and smoother mid-high frequencies — a different route to good sound than FiiO's dynamic driver, and one that tends to favor control and consistency over raw excursion.
The feature list is where it runs away from the FiiO. Dolby Atmos with head tracking means spatial audio that responds to head movement — turn left and the soundstage shifts so audio arrives from your right. For movies and games this is genuinely transformative in a way a wired stereo IEM can't replicate. Add 3-point multipoint so you can stay connected to three devices and prioritize whichever matters, a Voice Focus AI chip for call clarity, and AI-driven sound adaptation to your environment, and you have a device built for a day in motion.
Battery is the headline practical number: up to 10 hours of playback with noise cancelling on, and 28 hours total with the charging case, which itself supports wireless charging. Technics also states the AZ100 is 10% smaller and 16% lighter than its own AZ80, with a lower-profile shape — at 1.76 ounces for the pair, that's a fit story, not just a spec-sheet note, and fit is what makes or breaks a sealed wireless bud.
Who should buy it: commuters, travelers, hybrid workers and anyone who takes a lot of calls. The adaptive noise cancelling, multipoint and head-tracked spatial audio all solve real daily problems. Who should skip it: purists who want a detachable cable, a user-replaceable connection, or zero dependence on a battery. The AZ100 has no headphone jack and a plastic enclosure — it's built to disappear into your pocket, not to sit on a desk as a reference tool.
• Best for critical, wired listening → FiiO FD15. A 13.8 mm metal-dome dynamic driver, Tesla Valve bass loading and a Furukawa 22AWG MMCX cable are all aimed at sound quality first.
• Best for travel, commuting and calls → Technics Reference Class Hi-Fi. Adaptive noise cancelling, Voice Focus AI and 3-device multipoint cover the whole day.
• Best for movies and spatial audio → Technics Reference Class Hi-Fi. Dolby Atmos with head tracking is something the FD15 simply doesn't offer.
• Best for battery-free, always-ready use → FiiO FD15. No charging, no pairing, no firmware — plug in and play.
• Best for long sessions away from a charger → Technics Reference Class Hi-Fi. Up to 10 hours per charge, 28 with the case, plus wireless charging.
• Best for cable tinkerers and tip rollers → FiiO FD15. Detachable MMCX plus vocal and balanced eartips in three sizes each give you room to tune.
• Best for fit flexibility in a small package → Technics Reference Class Hi-Fi. A lower-profile shell that's smaller and lighter than the AZ80.
• Best for high-frequency range on paper → Technics Reference Class Hi-Fi. Its 20Hz–40kHz rating covers a wider span than the FD15's dynamic driver is specified for.
If I could only own one, I'd buy the Technics Reference Class Hi-Fi. Not because it out-resolves a purpose-built wired IEM — it probably doesn't — but because it does more of the things I actually do in a day: block noise, take calls, switch between laptop and phone, and throw head-tracked spatial audio at a film. In my opinion the FiiO FD15 is the better listening device and the smarter buy for anyone with a good source and a quiet room; the Technics is the better everyday device. If your listening happens at a desk, choose the FD15. If it happens on the move, choose the AZ100.
FAQ
Only the Technics has noise cancelling at all — adaptive noise cancelling that Technics says adjusts to your environment. The FiiO FD15 lists no noise control, so its isolation depends entirely on how well the eartips seal.
Technics rates it at up to 10 hours of playback with noise cancelling on, and up to 28 hours total when you include the charging case. The case supports wireless charging. The FiiO FD15 has no battery because it's a wired earphone.
The Technics, clearly. It has a Voice Focus AI chip for voice clarity and 3-point multipoint so you can take a call while connected to other devices. The FD15's remote control is limited, and it has no noise cancelling to help the person on the other end hear you in a loud place.
I don't quote prices here — check the current price on Amazon for both, since wired IEMs and flagship wireless earbuds sit in very different brackets. Decide first whether you want a cable or a battery, then compare what each costs.
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See also: FiiO K9 vs Jabra Evolve3, FiiO SnowSky/ Echo MINI vs OneOdio Focus A6, Generic Sonicast PRO Reference vs Linsoul Kiwi Ears Halcyon