If you want an open, wired listening setup with a sound-first design, choose Sennheiser HD 505; if you need wireless convenience and active noise cancellation for calls, choose CMF BY NOTHING Headphone Pro Active. The HD 505 is the clearer fit for listening at a desk; CMF is the more adaptable everyday headset. Neither sheet specifies a microphone, so call handling itself should not be assumed from these features.
If you want an open, wired listening setup with a sound-first design, choose Sennheiser HD 505; if you need wireless convenience and active noise cancellation for calls, choose CMF BY NOTHING Headphone Pro Active. The HD 505 is the clearer fit for listening at a desk; CMF is the more adaptable everyday headset. Neither product information sheet specifies a microphone, so don’t assume either model’s call performance from these features alone.
• Sennheiser HD 505: Open-back cups and a wired connection suit focused listening; no wireless connection or noise control is listed.
• CMF BY NOTHING Headphone Pro Active: Bluetooth 5.4, adaptive ANC and Transparency Mode offer flexibility; its listed weight is 283 g, compared with 237 g for the HD 505.
• Sennheiser HD 505: A 1.80 m cable, 3.5 mm plug and included 6.35 mm adapter make it a straightforward choice for compatible wired gear.
• CMF BY NOTHING Headphone Pro Active: Up to 50 hours of wireless playback with ANC on and up to 100 hours without it reduce the need to recharge frequently.
• Choose HD 505 for cable-connected listening at a desk; choose CMF for wireless listening, noise cancellation and travel-friendly flexibility.
The HD 505 is a wired, over-ear headphone built around an open-back design. Sennheiser describes its sound as detailed and controlled, with forward-angled transducers intended to create a more spacious presentation. The stated frequency range is 20 Hz–20,000 Hz. That design points toward music, movies and games where an open, natural-feeling presentation matters more than blocking outside noise.
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We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
At 237 g, it is lighter than the CMF model in this comparison. The synthetic leather headband and velour ear cushions are intended to make extended listening more comfortable. A 1.80 m cable with a 3.5 mm plug is included, along with a screw-on 6.35 mm adapter. I’d consider it for a desk setup, a compatible audio system or gaming where a cable is welcome and wireless features are unnecessary.
Skip the HD 505 if you want Bluetooth, active noise cancellation or the option to switch to transparency mode. Its listed noise control is none, and its connection is wired. Open-back cups also make it a poor match for anyone who wants a closed-off listening experience in a noisy setting. For calls, the listed facts don’t establish microphone or call-control features, so I wouldn’t choose it specifically as a call headset based on this information.
CMF’s Headphone Pro is the more feature-packed wireless option. It uses Bluetooth 5.4, supports LDAC, and includes hybrid active noise cancellation with up to 40 dB of adaptive noise reduction. A Transparency Mode lets ambient sound through when you want to hear more of your surroundings. Its 40 mm dynamic drivers and 20 Hz–96 kHz stated frequency range are part of a broader listening feature set that also includes custom EQ and spatial audio through the Nothing X app.
The headline practical advantage is battery life: CMF lists up to 50 hours of playback with ANC on and up to 100 hours without it. The headphones weigh 283 g and use memory foam earpads. They can connect over Bluetooth or AUX, and the supplied information lists compatibility with iOS, Android, macOS and Windows. That makes this the more flexible choice for moving between devices, commuting, travel or listening around the house without a cable.
Choose CMF if you want wireless convenience, adjustable sound features and a way to reduce surrounding noise. Skip it if a lighter listed weight or an open-back design is your priority, or if you want a simple wired headphone without app-based customization. Although it is described as a headset and offers voice-assistant controls, the product information provided does not specify a microphone. ANC can help make listening less distracting, but it does not by itself prove how clearly your voice will come through on calls.
• Best for a wired desk setup → Sennheiser HD 505. Its 1.80 m cable, 3.5 mm plug and included 6.35 mm adapter are the relevant details if your listening gear uses a headphone jack.
• Best for wireless listening → CMF BY NOTHING Headphone Pro Active. Bluetooth 5.4 and AUX give it two connection options, while the HD 505 is wired.
• Best for reducing outside noise → CMF BY NOTHING Headphone Pro Active. It offers adaptive ANC rated up to 40 dB and a separate Transparency Mode. The HD 505 lists no noise control.
• Best for a lighter listed design → Sennheiser HD 505. Its stated weight is 237 g; CMF’s is 283 g. Weight alone cannot tell you how either will feel on your head, but it is a concrete difference.
• Best for long stretches away from a charger → CMF BY NOTHING Headphone Pro Active. Its listed playback is up to 50 hours with ANC on or 100 hours without ANC.
• Best for sound customization → CMF BY NOTHING Headphone Pro Active. Custom EQ, a Personal Sound Profile and spatial audio features are part of its app-based feature set.
• Best for an open-back listening style → Sennheiser HD 505. Its open cups and forward-angled transducers are designed for a spacious presentation, rather than noise isolation.
• Best for calls? Check the microphone details before choosing either. Neither product information sheet specifies a microphone or call performance. CMF is more convenient for wireless use, but that doesn’t establish that it is the best Bluetooth headphones for calls or the best headset for calls.
The phrase “sleep headphones for calls” also raises a practical distinction: neither product is described as sleep-specific, and neither sheet gives a microphone specification for calls. Both are over-ear models, so the provided details are not enough to establish comfort for sleeping or suitability for voice calls while lying down.
I’d choose the CMF BY NOTHING Headphone Pro Active for general everyday use because wireless connection, ANC, Transparency Mode and long listed battery life make it the more adaptable option. For calls, though, I’d verify the microphone and call controls before buying; those details aren’t specified here. If I wanted wired listening, a lighter listed weight and open-back sound instead, I’d choose the Sennheiser HD 505.
FAQ
Yes. It has hybrid adaptive active noise cancellation rated up to 40 dB, plus Transparency Mode for letting more ambient sound through. The Sennheiser HD 505 lists no noise-control feature.
The CMF model is wireless and lists up to 50 hours with ANC on or up to 100 hours without ANC. The HD 505 is wired, so it does not have a battery-life figure to compare.
No. The HD 505 is a wired headphone with a 1.80 m cable and 3.5 mm plug; a 6.35 mm screw-on adapter is also included. CMF supports Bluetooth 5.4 as well as AUX.
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