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We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-10-09 · 8 min read · Independent comparison
• Bowers & Wilkins Pi7 — biggest strength: a genuine true-wireless earbud package built for listening on the move, with 9.2mm hybrid drivers, active noise cancellation, three call-clarity microphones and aptX Adaptive over a 24-bit connection.
• Bowers & Wilkins Pi7 — biggest trade-off: it is a sealed in-ear design, so it depends on a good tip fit for comfort and isolation, and it is not marketed as a waterproof swimming or heavy-sweat product.
• FiiO DM15 — biggest strength: a transportable hi-fi source with a 24-bit R2R DAC, up to 1150mW per channel of balanced output and aptX Adaptive Bluetooth transmission from CD or USB input.
• FiiO DM15 — biggest trade-off: it is a source device, not something you wear. At 0.8 kg it is portable in the "carry it in a bag" sense, not the "put it in your pocket and go for a ride" sense.
• Pick Bowers & Wilkins Pi7 if you want headphones you actually wear — for music, calls, commuting and cycling.
• Pick FiiO DM15 if you want to feed high-quality audio into headphones or speakers you already own, from CDs, USB files or a Bluetooth link.
The Pi7 S2 is the second generation of Bowers & Wilkins' flagship true wireless earbuds, and the spec sheet reads like a product designed around one idea: make wireless listening sound as good as it can. Inside each bud sits a 9.2mm hybrid driver with its own amplifier and dedicated DSP. That combination of a hybrid driver plus per-driver amplification is unusual in a true wireless design, and it's the kind of engineering that tends to pay off in separation between instruments and control in the low end.
Connectivity is where the aptX Adaptive story lives. The Pi7 S2 runs a 24-bit connection over Qualcomm aptX Adaptive with a revised antenna design, and Bowers & Wilkins quotes stable connectivity up to 25 metres. Audio latency is listed at 20 milliseconds, which matters if you watch video or play games on your phone — that's low enough that lip-sync drift is unlikely to bother you. Bluetooth version is 5, and the buds charge over USB-C.
Noise cancellation is adaptive: you can change the level of cancellation with a button press depending on where you are. There are three microphones tuned for call clarity, and touch controls handle media, volume and calls. Battery life is quoted at 16 hours, with the charging case also quoted at 16 hours and a 15-minute charge time — a quick top-up before you head out the door.
Who should buy it: anyone who wants one pair of earbuds to cover music, phone calls and daily movement — commuting, gym sessions, and especially as sports earbuds for cycling, where the adaptive noise cancellation and low latency are genuinely useful.
Who should skip it: if you need a device that plays physical CDs, or you want a dedicated desktop DAC/amp to drive power-hungry over-ear headphones, the Pi7 can't do either job. It's a listening device, not a source.
FiiO DM15: Who It's For
The FiiO DM15 is a very different animal. It's a portable stereo CD player that also works as a USB DAC and a Bluetooth transmitter, built around a fully differential complementary 24-bit R2R resistor-array DAC. FiiO says it uses 192 resistors with 0.1% precision and low temperature drift, and the goal is explicit: restore the warmth, smoothness and analog character people associate with classic portable CD players.
The headline number is output power. The DM15 delivers up to 1150mW per channel in balanced output, which is enough to drive demanding over-ear headphones — something portable players rarely manage. Compared with the previous generation, FiiO reduced the thickness by 2mm while increasing performance, so it's still meant to be carried rather than parked on a desk. Weight is 0.8 kg, which is realistic for what's inside but worth being honest about: this is a bag item, not a pocket item.
Bluetooth is handled by Qualcomm's QCC3095 chipset, supporting aptX, aptX HD, aptX Adaptive and SBC. The important detail is that both CD input and USB input can be transmitted over Bluetooth — so the DM15 can act as a wireless bridge between a disc or a computer and a pair of aptX Adaptive headphones or earbuds. There's a visual interface for pairing and switching devices.
In USB DAC mode it handles up to 384kHz/32-bit PCM and DSD256, so it works as a proper desktop or laptop sound card, not just a CD spinner. And there's a tuning playground: 24 total sound combinations from a 3-stage bass boost and 8 EQ presets, plus a RETRO mode tuned for a vintage analog flavour.
Who should skip it: if you want earbuds to wear while moving, this isn't it. There's no headphone jack on the unit itself in the traditional sense — the data sheet lists headphones jack as "No," so plan around its Bluetooth and USB roles. It also only lists MP3 among supported audio formats on the sheet, so if your library is built on other codecs, verify compatibility before buying. It's not a fitness product in any way.
Side-by-Side: Which Should You Choose?
• Best for wearing while cycling → Bowers & Wilkins Pi7. Sealed in-ear fit, adaptive noise cancellation and 20ms latency make it the one you can actually ride with.
• Best for playing your CD collection → FiiO DM15. It has a disc drive and a 24-bit R2R DAC. The Pi7 has neither.
• Best for phone calls → Bowers & Wilkins Pi7. Three microphones are dedicated to call clarity, plus touch call controls.
• Best for driving demanding over-ear headphones → FiiO DM15. Up to 1150mW per channel balanced.
• Best as a wireless audio bridge → FiiO DM15. It can transmit CD and USB audio over aptX Adaptive Bluetooth.
• Best for streaming apps without a phone in the chain → Bowers & Wilkins Pi7. The Music App streams directly from supported services.
• Best for tweaking your sound signature → FiiO DM15. 24 sound combinations, 8 EQ presets and a RETRO mode.
• Best for travel and daily carry → Bowers & Wilkins Pi7. A charging case that fits a pocket versus a 0.8kg box.
If you're shopping for headphones — the thing that actually goes on your head — I'd buy the Bowers & Wilkins Pi7. In my opinion it's the more versatile product by a wide margin: hybrid drivers with individual amps, adaptive noise cancellation, three call microphones, 20ms latency, aptX Adaptive over a 24-bit connection, and a charging case that can even retransmit audio from a wired source. For music, calls and riding, it covers the whole day.
I'd choose the FiiO DM15 only if your needs are the opposite: you want a source, not a speaker. If you have CDs, a headphone collection that needs real power, and a use for aptX Adaptive transmission, it's a genuinely interesting piece of kit.
For cycling specifically, the Pi7 is the one I'd recommend — it's built for the job, and the DM15 simply isn't.
FAQ
aptX Adaptive is a Qualcomm Bluetooth codec that adjusts bitrate and latency based on what you're doing — higher quality for music, lower latency for video and gaming. Both the Bowers & Wilkins Pi7 and the FiiO DM15 support it, but in different roles: the Pi7 receives it, while the DM15 can transmit it from CD or USB input.
Based on the specs, the Bowers & Wilkins Pi7 fits cycling better than the DM15, which isn't wearable at all. The Pi7 offers a sealed in-ear fit, adaptive active noise cancellation you can adjust with a button, 20ms latency and 16 hours of quoted battery life.
The Bowers & Wilkins Pi7 data sheet doesn't list an IP or waterproof rating, so I can't claim it's IPX7 — don't assume it is. Treat it as a well-built pair of earbuds for normal active use rather than something to submerge.
Neither data sheet lists built-in voice assistant support. The Pi7 does give you touch controls for media, volume and calls, plus three call-clarity microphones, which is what matters most for taking calls on the move.
Whichever way you lean, check the current price on Amazon before you commit — the numbers move, and the specs above are what should drive your decision.
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