If you want open-air audio with deep, natural bass and zero ear pressure for long listening sessions, choose Audio-Technica ATH-AD500X; if you need a portable, noise-isolating pair with built-in call controls for commuting or workouts, choose Sennheiser HD 400U.
• Audio-Technica ATH-AD500X: Delivers an expansive, natural soundstage with lightweight aluminum construction but lacks any passive noise isolation due to its open design.
• Sennheiser HD 400U: Offers a compact, foldable build with a smart remote for calls and music while blocking out background noise, though it sacrifices the airy openness of the AT model.
• Who should buy the ATH-AD500X: Audiophiles who prioritize vocal clarity and immersive music experiences in quiet environments.
• Who should buy the HD 400U: Commuters, travelers, or anyone needing secure fit and noise reduction during active use like open ear earbuds for workout scenarios where portability matters.
The Audio-Technica ATH-AD500X is engineered for those who treat music as an event rather than just background noise. Its newly designed 53 mm drivers, paired with CCAW voice coils, are tuned to reproduce remarkably natural sound with a specific focus on deep, impactful bass and outstanding vocal projection. If you sit down to listen to a full album, these headphones create a sonic landscape that feels wide and unconfined. The open-air design means there is absolutely no sense of pressure on your ears, resulting in a completely natural sensation that many listeners find essential for marathon listening sessions.
Comfort is a major selling point here. The self-adjusting 3D Wing Support Housing works to provide comfortable support regardless of head shape, ensuring the weight is distributed evenly. This is backed by flexible raised-fabric earpads that offer excellent wearing comfort and durability over time. The entire chassis utilizes a lightweight honeycomb aluminum casing, which keeps the unit from feeling heavy despite its robust build. You also get a highly conductive OFC single-sided cable with an elastic TPE sheath specifically designed to prevent tangles, a practical detail that saves frustration when setting up your gear.
We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-10-29 · 6 min read · Independent comparison
However, this product is not for everyone. Because they are open-air headphones, they do not isolate sound. Anyone looking for ANC earbuds for workout sessions or trying to block out a noisy gym environment will find these useless. They leak sound, meaning people around you can hear what you are playing, and outside noise will bleed into your mix. Furthermore, they require a wired connection via a gold-plated stereo 1/8" connector (with a 1/4" adapter included), so you cannot use them wirelessly without an external dongle. If you value silence and privacy, skip this model entirely.
The Sennheiser HD 400U takes a different approach, focusing on utility and versatility for the modern listener who moves around frequently. The closed-back design and ergonomic ear cushions are explicitly intended to reduce background noise, offering a form of passive noise cancellation that helps you focus on your content even in busy environments. This makes them a strong contender for those who need bluetooth earbuds for workout alternatives that stay secure and don't let the world in. The one-button smart remote conveniently located on the cable allows you to control music and take calls with ease, removing the need to fumble with your phone while on the move.
Portability is another key strength. These headphones feature a sturdy folding design, making them durable and compact enough to be taken anywhere. Whether you are packing them into a carry-on bag or tossing them into a gym duffel, the foldable mechanism ensures they take up minimal space. At only 217 grams, they are significantly lighter than the Audio-Technica option, which reduces neck strain during extended wear while traveling. The inclusion of a protective case in the package further underscores their travel-ready nature, ensuring they remain pristine when not in use.
The trade-off lies in the audio character compared to the open-air competitor. While the sensitivity of 120 dB ensures impressive detail, the frequency range of 20 Hz to 20,000 Hz is slightly more standard than the extended lows of the ATH-AD500X. The plastic and fabric enclosure material feels solid but less premium than the aluminum build of the AT. Additionally, the connectivity is strictly wired via USB-C, which might limit compatibility with older devices unless you have the right adapter. If you need a headphone that stays put during a run and blocks out the hum of traffic, this is the tool for the job.
• Best for natural soundstage and vocal clarity → Audio-Technica ATH-AD500X (thanks to 53 mm drivers and open-air design).
• Best for noise isolation and commuting → Sennheiser HD 400U (closed-back design provides passive noise cancellation).
• Best for portability and travel → Sennheiser HD 400U (foldable design includes a protective case).
• Best for long-duration comfort in quiet rooms → Audio-Technica ATH-AD500X (zero pressure sensation and wing support).
• Best for hands-free calling → Sennheiser HD 400U (built-in microphone and smart remote control).
• Best for durability against tangles → Audio-Technica ATH-AD500X (elastic TPE sheath on the cable).
• Best for lightweight feel → Sennheiser HD 400U (weighs 217g vs 0.5kg for the AT).
• Best for open ear earbuds for workout scenarios (as a substitute) → Sennheiser HD 400U (due to secure fit and noise reduction).
In my opinion, I would choose the Sennheiser HD 400U for most users today, primarily because of its versatility and ability to handle real-world distractions. While the Audio-Technica ATH-AD500X offers superior audio fidelity for critical listening in a controlled room, its lack of noise isolation limits its usefulness. The Sennheiser model, with its foldable design, smart remote, and closed-back sound profile, fits better into a dynamic lifestyle. Specifically, if you are looking for open ear earbuds for workout situations where you need to stay aware of your surroundings but still block out wind or ambient noise, the HD 400U is the practical winner. It bridges the gap between high-quality audio and functional daily use far better than the open-air alternative.
Both models are wired headphones. The Audio-Technica uses a 3.5mm jack with a 6.3mm adapter, while the Sennheiser connects via USB-C, requiring a physical cable for all audio and control functions.
No. Neither product features active electronic noise cancellation. The Sennheiser HD 400U relies on its closed-back design for passive noise isolation, while the Audio-Technica ATH-AD500X is fully open-air and lets all ambient sound through.
The Sennheiser HD 400U is significantly lighter at 217 grams compared to the 0.5 kg Audio-Technica. Combined with its foldable frame and included protective case, it is the clear choice for travelers.
While neither is a true "open ear earbud," the Sennheiser HD 400U is more suitable for active use due to its secure closed-back fit and noise isolation properties, whereas the open design of the Audio-Technica makes it impractical for gyms or outdoor runs.
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