Audio T Verdict
The Sennheiser HD 400S are refreshingly straightforward headphones. There is no Bluetooth, battery, app or noise-cancelling circuitry to worry about. Plug the detachable 3.5mm cable into a compatible source and you are ready to listen.
The closed-back around-ear design gives useful passive isolation and helps keep sound leakage under control, while the 18-ohm impedance makes them an easy match for phones, tablets, laptops, portable players and other everyday equipment with a conventional headphone output. At just 217g and with a folding design, they are also considerably easier to carry around than many full-sized hi-fi headphones.
Add the one-button remote and microphone for calls and playback control and the HD 400S make a lot of sense for somebody who simply wants a comfortable, affordable pair of wired Sennheisers for music, films, work and everyday listening.
Closed-Back Does Not Mean Active Noise Cancelling
The HD 400S reduce some external sound naturally through their closed earcups and around-ear fit, but they do not feature electronic Active Noise Cancellation. If you specifically want ANC for commuting or travel, consider a wireless model such as the Sennheiser ACCENTUM Wireless.
Sennheiser HD 400S Headphones
The Sennheiser HD 400S are lightweight closed-back wired headphones designed for straightforward everyday listening at home, work or on the move.
The around-ear design helps reduce surrounding noise without electronic processing, while Sennheiser's dynamic transducers provide an extended response from 18Hz to 20kHz with a full-bodied low end and clear presentation.
A detachable 1.4m cable incorporates a one-button remote and omnidirectional microphone for compatible calls and music control, while the folding earcups make the HD 400S easier to store when not in use.
- Closed-back around-ear headphones
- Dynamic transducer design
- 18Hz to 20kHz frequency response
- 18-ohm impedance
- 120dB SPL at 1kHz / 1V RMS
- Less than 0.5% THD
- Passive noise isolation
- Detachable single-sided cable
- 1.4m cable length
- One-button inline remote
- Built-in omnidirectional microphone
- 3.5mm angled jack plug
- Foldable construction
- 217g weight
- No battery required
- No Bluetooth required
Simple Wired Listening
The HD 400S are completely passive headphones.
There is no pairing process, battery to charge or wireless connection to manage. Connect the 3.5mm plug to a compatible headphone output and the source device provides the signal and amplification.
That simplicity can be particularly useful if you want headphones that are always ready to use.
No Battery to Charge
Because the HD 400S contain no wireless electronics or Active Noise Cancellation system, they do not require a rechargeable battery.
This removes one of the main limitations of wireless headphones: if your source has a suitable headphone output, the HD 400S can simply keep playing.
Closed-Back Around-Ear Design
The rear of each earcup is enclosed rather than acoustically open.
This closed construction helps reduce the amount of surrounding noise reaching your ears and limits the amount of music escaping into the room.
That makes the HD 400S more practical than an open-back hi-fi headphone in environments such as:
- Offices
- Shared rooms
- Public transport
- Libraries
- Bedrooms
- Home working spaces
Passive Noise Isolation
The isolation comes from the physical earcups and earpads rather than microphones and electronic processing.
This means there is no ANC circuitry altering the incoming signal and no battery power required to achieve the basic reduction in external sound.
Closed-Back or Open-Back?
Closed-back headphones such as the HD 400S are generally the more practical choice when other people are nearby or when there is background noise to contend with. Open-back headphones normally provide a more spacious presentation but leak considerably more sound and offer very little isolation. You can read more in our Audio T guide to open and closed-back headphones.
Dynamic Sennheiser Sound
Sennheiser uses dynamic transducers within the HD 400S, with the current specification giving a frequency response from 18Hz to 20kHz.
The tuning is intended to provide strong bass alongside clear midrange and treble, making the headphones suitable for a wide variety of music rather than one particular genre.
18-Ohm Impedance
The HD 400S have a nominal impedance of just 18 ohms.
This makes them considerably less demanding than high-impedance hi-fi models such as the 300-ohm HD 600 and means they are intended to work comfortably with everyday portable equipment.
Suitable sources can include:
- Smartphones with a suitable 3.5mm output or adapter
- Tablets
- Laptops
- Desktop computers
- Portable music players
- Games controllers with suitable headphone sockets
- Hi-fi equipment with conventional headphone outputs
120dB SPL Sensitivity
Sennheiser specifies a sound pressure level of 120dB SPL at 1kHz and 1V RMS.
Combined with the low 18-ohm impedance, the HD 400S are designed to achieve useful listening levels from relatively modest headphone outputs.
Low Distortion
Total harmonic distortion is specified below 0.5% at 1kHz and 100dB SPL.
This helps the transducers reproduce the incoming signal cleanly rather than adding excessive unwanted harmonic information of their own.
217g Lightweight Construction
The HD 400S weigh approximately 217g.
That is relatively light for full-sized around-ear headphones and helps make them comfortable to wear for longer periods.
The low weight is also useful when the headphones are being carried in a work bag or backpack.
Foldable Design
The earcups fold inwards to reduce the amount of space occupied when the headphones are not being worn.
This makes the HD 400S more practical for portable use than a rigid full-sized headphone that always occupies its complete wearing dimensions.
Detachable RCS 400 Cable
Sennheiser supplies the HD 400S with its detachable RCS 400 single-sided cable.
The cable is approximately 1.4m long and terminates in an angled 3.5mm stereo connection.
Being detachable also means cable damage does not necessarily mean replacing the entire pair of headphones.
Single-Sided Cable
The cable connects to one earcup rather than splitting externally between both sides.
This keeps the cable arrangement simple and reduces the amount of wire hanging around the listener during everyday use.
One-Button Smart Remote
An inline one-button remote provides convenient control with compatible devices.
Depending on the connected device and application, it can be used for functions such as:
- Playing music
- Pausing music
- Answering compatible calls
- Ending compatible calls
Built-In Microphone
The cable also contains an omnidirectional microphone for compatible voice calls.
Its specified frequency response extends from 100Hz to 10kHz, covering the important speech frequencies required for everyday communication.
Useful for Working From Home
The combination of a closed-back design, lightweight construction and inline microphone makes the HD 400S particularly practical for computer-based work.
You can use the same headphones for music between meetings and compatible voice calls without needing a separate desktop microphone or wireless headset.
Useful for Films and Video
A wired connection avoids the Bluetooth latency that can sometimes cause picture and sound to fall out of sync.
That makes the HD 400S useful for watching films, television or online video from a laptop, tablet or another source with a suitable headphone output.
Useful for Gaming
The HD 400S can also be used with compatible games controllers, computers and consoles that provide a suitable 3.5mm headset connection.
The inline microphone can provide voice functionality where the device supports the cable's headset connection.
They are not marketed as a dedicated gaming headset, but their lightweight closed-back construction makes them a useful general-purpose option.
Useful for Travel
The folding design and 217g weight make the HD 400S relatively easy to carry.
Unlike a wireless headphone, there is also no concern about arriving at the start of a journey with an empty battery.
The closed-back earcups provide some passive reduction of surrounding sound, although they will not suppress steady aircraft or train noise as strongly as a good Active Noise Cancelling headphone.
HD 400S or Sennheiser HD 569?
HD 400S
- Closed-back
- Around-ear
- 18-ohm impedance
- 18Hz to 20kHz response
- 217g
- Foldable
- 1.4m detachable cable
- Inline remote and microphone
- 3.5mm connection
- Designed for everyday portable use
HD 569
- Closed-back
- Around-ear
- Larger home-focused design
- Sennheiser E.A.R. acoustic system
- Replaceable soft ear cushions
- 3m home cable supplied
- Additional shorter cable with remote and microphone
- Greater flexibility between home and portable use
- More substantial hi-fi design
- Step-up option within the wired range
Which Should You Choose?
The HD 400S are the simpler and more affordable choice if portability, low weight and straightforward phone, tablet or laptop listening are the priorities.
The Sennheiser HD 569 are worth stepping up to if your listening is more heavily focused around a home hi-fi system and you want a larger, more substantial closed-back headphone with additional cable options.
HD 400S or ACCENTUM Wireless?
The two products approach everyday headphone listening in very different ways.
The HD 400S provide simple passive wired operation with no battery, wireless connection or ANC.
The ACCENTUM Wireless add Bluetooth, Hybrid Active Noise Cancellation, Transparency Mode, app-based EQ and a rechargeable battery for customers who prioritise wireless convenience.
Why Choose Wired Headphones?
Wireless headphones are enormously convenient, but traditional wired designs still have practical advantages.
- No battery charging
- No Bluetooth pairing
- No wireless codec compatibility to consider
- No firmware updates required
- No wireless latency
- Simple connection to compatible equipment
- Potentially longer useful life without a rechargeable battery ageing
Check Your Device Has the Right Connection
The HD 400S use a conventional 3.5mm analogue connection.
Many current smartphones and some tablets no longer provide a built-in headphone socket, so an appropriate USB-C or Lightning headphone adapter may be required.
Using a Phone Without a Headphone Socket
A suitable digital-to-analogue headphone adapter can allow the HD 400S to be used with phones and tablets that only provide USB-C or Lightning. Check that the adapter supports both stereo audio and microphone functions if you want to use the HD 400S inline mic for calls.
No App Required
There is nothing to configure before listening.
The HD 400S have no digital signal processing, equaliser app or firmware settings. Any tonal adjustment is carried out by the source device or playback software if desired.
No Active Electronics to Become Obsolete
The passive wired design also means the headphones do not depend on continued support for a wireless standard, operating-system app or rechargeable battery.
The detachable cable gives an additional degree of serviceability compared with headphones where the cable is permanently fixed into the enclosure.
Who Are the Sennheiser HD 400S For?
- Listeners wanting affordable wired Sennheiser headphones
- People wanting a lightweight around-ear design
- Students
- Working-from-home users
- Laptop and computer listening
- Phones and tablets with suitable headphone outputs or adapters
- Listeners wanting an inline microphone
- People who do not want to manage a rechargeable battery
- Travellers wanting foldable wired headphones
- Users wanting more isolation than an open-back headphone provides
- Everyday music, films and podcasts
Who Are They Not For?
- Listeners wanting Bluetooth
- Customers wanting Active Noise Cancellation
- People wanting app-based sound adjustment
- Listeners seeking a dedicated reference hi-fi headphone
- Customers requiring maximum isolation for aircraft or noisy travel
- Devices without a compatible analogue output or suitable adapter
- Listeners specifically wanting an open-back presentation
Key Features
- Sennheiser HD 400S
- SKU 508598
- Wired headphones
- Closed-back acoustic design
- Around-ear fit
- Dynamic transducers
- 9.7mm specified transducer size
- 18Hz to 20kHz frequency response
- 18-ohm impedance
- 120dB SPL at 1kHz / 1V RMS
- Less than 0.5% THD
- Passive noise isolation
- Foldable construction
- 217g weight
- Detachable cable
- RCS 400 cable supplied
- Single-sided cable
- 1.4m cable length
- Angled 3.5mm jack plug
- One-button inline remote
- Inline microphone
- Omnidirectional microphone
- 100Hz to 10kHz microphone response
- Music playback control
- Compatible call control
- No Bluetooth
- No rechargeable battery
- No Active Noise Cancellation
- No app required
- 12-month manufacturer's warranty
Frequently Asked Questions
Are the Sennheiser HD 400S still current?
Yes. The HD 400S remain part of Sennheiser's current wired headphone range.
Are the HD 400S wireless?
No. They are passive wired headphones using a 3.5mm analogue connection.
Do they have Bluetooth?
No.
Do they need charging?
No. The HD 400S contain no rechargeable battery.
Are the HD 400S noise cancelling?
No. They do not have electronic Active Noise Cancellation.
Do they block outside noise?
The closed-back around-ear construction provides useful passive isolation, but it is not equivalent to electronic ANC.
Are they over-ear or on-ear?
They are around-ear / over-ear headphones.
Are they open-back or closed-back?
Closed-back.
What is the frequency response?
18Hz to 20kHz.
What impedance are the HD 400S?
18 ohms.
Do I need a headphone amplifier?
Generally no. Their low 18-ohm impedance is intended to work with everyday portable and computer headphone outputs, although the final result will still depend on the source device.
Can I use them with a smartphone?
Yes, provided the phone has a compatible 3.5mm output or an appropriate headphone adapter.
Can I use them with an iPhone?
Yes, with a suitable Apple-compatible analogue headphone adapter on iPhones without a 3.5mm socket.
Can I use them with USB-C phones?
Yes, with a compatible USB-C headphone DAC/adapter where required.
Do they have a microphone?
Yes. The supplied cable incorporates an omnidirectional microphone.
What is the microphone frequency response?
100Hz to 10kHz.
Can I take phone calls?
Yes, with compatible devices. The supplied cable includes a microphone and one-button smart remote.
Can I control music from the cable?
Yes. The one-button remote supports compatible music playback control.
Does the remote control volume?
No dedicated volume-up and volume-down controls are specified. It is a one-button remote.
Is the cable removable?
Yes. The supplied RCS 400 cable is detachable.
How long is the cable?
Approximately 1.4 metres.
What plug does it use?
An angled 3.5mm plug.
Do the headphones fold?
Yes. The folding design makes them easier to store and transport.
How much do the HD 400S weigh?
Approximately 217g.
Are they good for travelling?
The folding design, low weight and closed-back construction make them practical for travel, although they do not provide Active Noise Cancellation.
Are they good for working from home?
Yes. Their closed-back design, lightweight fit and inline microphone make them particularly useful for music and compatible calls from the same pair of headphones.
Can I use them for gaming?
Yes, with equipment that provides a compatible headset connection. They are not a dedicated gaming headset, but the inline microphone can be useful where supported.
Can I replace the cable?
Yes. The cable is detachable, and Sennheiser lists the RCS 400 as the corresponding cable accessory.
What is the difference between HD 400S and HD 569?
The HD 400S are lighter, foldable and more focused on affordable everyday portable listening. The HD 569 are a larger home-oriented closed-back design with additional cable options and a stronger emphasis on hi-fi listening comfort.
How long is the manufacturer's warranty?
Sennheiser currently lists the HD 400S within its 12-month manufacturer's warranty group, subject to the applicable warranty terms and proof of purchase.
What comes in the box?
The package contains the HD 400S headphones and detachable RCS 400 single-sided cable with one-button remote, microphone and angled 3.5mm plug.
Related Sennheiser Products and Audio T Guides
Why Buy the Sennheiser HD 400S From Audio T?
Choosing headphones is not only about the specification. Where you plan to use them, whether you need isolation, the connection on your phone or computer and whether wired or wireless operation makes more sense can all change which model is right for you.
Audio T can help you compare the HD 400S with other Sennheiser wired and wireless headphones, check connectivity with your equipment and decide whether a lightweight closed-back design is the best choice for the way you listen.
- Friendly headphone advice
- Wired and wireless headphone comparisons
- Open and closed-back guidance
- Phone and tablet compatibility advice
- 3.5mm connection guidance
- USB-C and Lightning adapter advice
- Working-from-home headphone guidance
- Travel headphone recommendations
- Sennheiser model comparisons
- Headphone demonstrations where available
- Ongoing after-sales support
Contact your local Audio T store if you would like help choosing the right Sennheiser headphones for your equipment and the way you listen.