If you want a set of wireless, noise-cancelling headphones that intelligently adapt to your environment and offer seamless connectivity for on-the-go use, choose Bowers & Wilkins FP39691; if you need an ultra-precise, wired electrostatic experience with unmatched frequency range for critical listening at home, choose Koss ESP/95X.
• Bowers & Wilkins FP39691: Its biggest strength is adaptive noise cancellation and 22 hours of wireless battery life, making it ideal for travel and commuting. The trade-off is that it requires an amplifier or dongle to reach its full potential in a wired setup and lacks the extreme frequency extension of electrostatic drivers. This pick is for the modern listener who needs versatility and smart features.
• Koss ESP/95X: Its biggest strength is its revolutionary electrostatic design delivering a frequency response from 8Hz to 35,000Hz for studio-grade accuracy. The trade-off is that it is strictly wired, requires a dedicated energizer (not included in the headphone package), and offers no active noise cancellation. This pick is for the audiophile who prioritizes absolute sound fidelity over convenience.
The Bowers & Wilkins FP39691, known as the PX, is engineered for the person who refuses to compromise between high-fidelity audio and the demands of daily life. At its core, this headphone utilizes drive units inherited from the brand's legendary P9 Signature series, but the real magic lies in its intelligent design. It features adaptive noise cancellation that actively adjusts to your surroundings, whether you are navigating a bustling city street, sitting on a plane, or trying to focus in a busy office. This isn't just about blocking out noise; it is about curating your soundscape so that the music remains pristine regardless of the chaos around you.
For the cyclist looking for rechargeable bone conduction alternatives or simply a secure, comfortable fit while moving, the PX offers a distinct advantage through its sensor technology. The device responds to your natural movements; lifting an ear cup instantly pauses the music, and placing it back down resumes playback. This "smart power" feature means you never have to fumble for buttons or worry about draining your battery while not listening. With a battery life of up to 22 hours with both Bluetooth and ANC active, and extending to nearly 30 hours without ANC, these headphones are built to last through long commutes, workdays, and travel days without needing a charge.
We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-10-24 · 7 min read · Independent comparison
However, this level of sophistication comes with specific requirements. The FP39691 relies on Bluetooth 4.1 with aptX-HD support for high-resolution streaming, which means you need a compatible source device to truly unlock its potential. While it includes a 3.5mm jack for wired listening, the true "best-in-class" performance often benefits from the companion app, which allows for firmware updates and EQ customization. If you are someone who values the ability to customize your sound profile digitally and wants a pair of headphones that feels like an extension of your smartphone ecosystem, this model is a perfect match. Conversely, if you prefer a purely analog, plug-and-play experience without apps or sensors, the complexity might feel unnecessary.
The Koss ESP/95X sits in a completely different category, designed exclusively for the purist who treats listening as a ritual rather than a background activity. This is not a headphone you wear while running errands or cycling; it is a piece of high-end audio equipment meant for a dedicated listening chair in a quiet room. The defining characteristic here is the electrostatic driver technology, which operates on a fundamentally different principle than dynamic drivers. By utilizing advanced damping materials and a proprietary diaphragm coating, the ESP/95X achieves a flat, full-range frequency response spanning from 8Hz to 35,000Hz. This means you hear details in recordings that standard dynamic drivers physically cannot reproduce, offering a clarity and accuracy that borders on scientific precision.
Comfort plays a massive role in why this product exists, especially given its weight. Weighing in at just 353 grams, it balances substance with a featherlight feel that allows for hours of fatigue-free listening. The construction features durable steel acoustical grills and premium velour-wrapped cushions, ensuring that even during marathon listening sessions, the pressure on your head remains negligible. The pivoting ear cups and adjustable headband further ensure a custom fit that seals comfortably around the ears. Unlike many other high-end headphones that feel heavy and rigid, the ESP/95X feels almost weightless once you adjust the headband correctly.
There is, however, a significant barrier to entry that defines who should buy this unit. The ESP/95X is an open-air design, meaning there is no isolation from outside noise. Furthermore, it is a wired-only solution that requires a specific E/90 Energizer to function, as electrostatic drivers cannot be powered by a standard headphone jack or portable player alone. You also lose the convenience of wireless freedom entirely. This product is for the individual who has a dedicated audio system, owns a compatible energizer, and cares more about the nuance of a violin string or the breath of a vocalist than the ability to walk around freely. If you are looking for best multipoint wireless headphones for cycling or any mobile application, this product will not meet your needs. But for the home enthusiast who wants the ultimate reference-quality sound, nothing else on the market offers this specific combination of low distortion and extended highs.
• Best for wireless freedom → Bowers & Wilkins FP39691, which uses Bluetooth 4.1 and aptX-HD for untethered listening.
• Best for frequency extension → Koss ESP/95X, reaching up to 35,000 Hz compared to the B&W's 20 kHz ceiling.
• Best for noise isolation → Bowers & Wilkins FP39691, featuring adaptive active noise cancellation for noisy environments.
• Best for pure audio fidelity → Koss ESP/95X, using electrostatic drivers for unparalleled detail and transparency.
• Best for travel and commuting → Bowers & Wilkins FP39691, with 22+ hour battery life and a protective case included.
• Best for stationary critical listening → Koss ESP/95X, designed for a fixed location with a dedicated energizer.
• Best for comfort during long sessions → Both excel, but Koss wins on weight (353g) while B&W wins on smart pause/resume sensors.
• Best for tech integration → Bowers & Wilkins FP39691, with app support for firmware updates and EQ tuning.
In my opinion, if I were buying a single pair of headphones for general use, including the specific scenario of riding a bike where I need to stay aware of traffic while enjoying music, I would choose the Bowers & Wilkins FP39691. The combination of adaptive noise cancellation, smart sensors that pause when you lift the cup, and a battery life that lasts all day makes it a practical tool for a modern lifestyle. While the Koss ESP/95X is undeniably a marvel of engineering with its electrostatic clarity, it is too restrictive for anyone who needs to move. The B&W PX transforms how you experience music by fitting into your life seamlessly, whereas the Koss demands that your life stop so you can listen. For a versatile, high-performance option that works anywhere, the Bowers & Wilkins FP39691 is the clear winner.
The Bowers & Wilkins FP39691 is far better suited for active use due to its wireless nature and secure over-ear design, though neither is specifically marketed as "bone conduction." The Koss ESP/95X is wired and open-back, making it unsafe and impractical for cycling.
Yes, the Koss ESP/95X requires a dedicated E/90 Energizer to power its electrostatic drivers, which is not always included in every bundle and must be purchased separately or verified in the listing. The Bowers & Wilkins FP39691 works directly with phones and computers via Bluetooth or a simple cable.
The Bowers & Wilkins FP39691 offers up to 22 hours of battery life with noise cancellation on, making it ideal for long flights or road trips. The Koss ESP/95X has no battery because it is a fully wired, passive electrostatic system that draws power from its external energizer.
Both support wired connections via a 3.5mm jack, so either can work with a laptop. However, the Bowers & Wilkins FP39691 adds the benefit of wireless Bluetooth connectivity and active noise cancellation, which helps block out room noise for a more immersive movie or game experience.
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