Audio T Verdict
The Sennheiser HD400S and HD400U make a sensible choice if you want comfortable, portable headphones that are ready whenever you are. A folding design, detachable cable and in-line microphone cover the everyday essentials, while the closed-back earcups provide useful passive isolation.
Choose the HD400S for a conventional 3.5mm headphone output, or the HD400U for direct USB-C listening from compatible devices. The USB-C version adds support for digital playback up to 24-bit/96kHz. Both keep things straightforward, with no headphone battery to charge or Bluetooth pairing to manage.
Sennheiser HD400S and HD400U Wired Over-Ear Headphones
The Sennheiser HD400S and HD400U combine a lightweight around-ear fit with the convenience of a wired connection. They are practical companions for music, podcasts, films and compatible calls, whether you are listening at a desk or taking them out for the day.
Select HD400S for 3.5mm or HD400U for USB-C. Your order includes one pair of headphones with the cable supplied for your chosen version.
Key Features
- Choice of connection: HD400S with 3.5mm jack or HD400U with USB-C.
- Closed-back over-ear design: Helps reduce surrounding sound and sound leakage.
- Dynamic Sennheiser drivers: 18Hz to 20kHz frequency response.
- Lightweight construction: Approximately 217g.
- Foldable design: Easier to store and carry.
- Detachable 1.4m cable: With in-line microphone and playback controls.
- No charging required: Wired listening without a built-in rechargeable battery.
- HD400U digital audio: Playback up to 24-bit/96kHz with a compatible source.
HD400S or HD400U: Which Version Should You Choose?
| Feature |
HD400S |
HD400U |
| Supplied connection |
Angled 3.5mm analogue jack |
USB-C digital audio |
| Typical source |
Equipment with a compatible headphone socket |
Compatible USB-C phones, tablets and computers |
| Digital playback support |
Determined by the source device before conversion to analogue |
Up to 24-bit/96kHz |
| Supplied cable |
Detachable 1.4m RCS 400 cable with one-button remote and microphone |
Detachable 1.4m USB-C cable with in-line remote and microphone |
If you mainly use a phone without a headphone socket, the HD400U offers a direct connection where USB audio is supported. For a portable player, hi-fi system or other equipment with a headphone output, the HD400S is the natural starting point.
Sennheiser Sound for Everyday Listening
The HD400S uses dynamic drivers with an extended response and an emphasis on energetic bass. For the HD400U, Sennheiser describes a balanced presentation with clear midrange, detailed treble and controlled low frequencies.
Both are designed for everyday listening across different types of music and spoken-word content. The HD400S's 18-ohm impedance makes it suitable for ordinary portable headphone outputs, without needing a separate headphone amplifier for everyday use.
USB-C Listening with the HD400U
The HD400U accepts digital audio through its supplied USB-C cable, supporting playback up to 24-bit/96kHz. Its class-compliant USB connection supports compatible devices running iOS, iPadOS, Android, ChromeOS, macOS, Windows and SteamOS.
Your device must support USB audio; the presence of a USB-C socket alone does not guarantee compatibility. Playback resolution also depends on your music, app and device settings.
Closed-Back Comfort and a Foldable Design
The around-ear cushions and enclosed earcups help reduce outside sound and keep more of your music to yourself. This passive isolation comes from the physical fit; neither model has active noise cancellation.
At approximately 217g, both versions are easy to carry, and the folding construction takes up less room in a bag. The HD400U also features soft, replaceable ear pads. For more about headphone designs, read our guide to open and closed-back headphones.
A Detachable Cable with Microphone and Remote
Both models have a removable 1.4m cable with an in-line microphone and remote for compatible calls and playback control. The HD400S uses Sennheiser's RCS 400 cable with a one-button remote, while the HD400U's USB-C cable includes a MEMS microphone.
The HD400U can also be used with a suitable optional analogue cable, available separately. This gives you another connection option if you move between USB-C devices and equipment with a headphone socket.
Frequently Asked Questions
What is the difference between the HD400S and HD400U?
The main difference is the supplied connection: 3.5mm analogue on the HD400S and USB-C digital audio on the HD400U. The HD400U also supports digital playback up to 24-bit/96kHz.
Will they work with my iPhone or iPad?
The HD400U connects directly to compatible USB-C-equipped iPhones and iPads. The HD400S needs a suitable USB-C-to-3.5mm or Lightning-to-3.5mm headphone adaptor when no headphone socket is provided. The supplied HD400U cable does not plug directly into Lightning devices.
Can I use the microphone with a hi-fi headphone socket?
A standard headphone-only output provides audio but does not support the microphone. On the HD400S, microphone use requires a compatible headset input or adaptor. Remote functions on both versions depend on your device and app.
Can I use the HD400U with a 3.5mm headphone output?
Yes, with a suitable optional analogue cable. The supplied cable is USB-C; an analogue cable is purchased separately.
Are both versions included?
No. Choose either HD400S or HD400U from the available options. Your order contains one pair of the selected model.
Explore More Sennheiser Headphones
Browse our Sennheiser range and headphone collection, or compare the Sennheiser HD 569 for a larger, home-focused closed-back design. Further manufacturer information is available on Sennheiser's HD400S and HD400U pages.
Why Buy Your Sennheiser Headphones from Audio T?
Our teams can help you check the connection on your equipment, explain adaptor requirements and compare wired or wireless alternatives. You also have the reassurance of our Audio T Price Promise and ongoing after-sales support.
Contact your local Audio T store for advice on choosing the right headphones for the way you listen.