Audio T Verdict
The Sennheiser HD 550 hit a very appealing sweet spot. They have the openness, detail and spacious imaging you would expect from a serious pair of Sennheiser hi-fi headphones, but without the weight, price or amplifier demands of some of the company's more exotic models.
The custom 38mm drivers are manufactured at Sennheiser's audiophile production facility in Ireland and angled towards the ears to create a wide, precise soundstage. The tuning is deliberately balanced rather than showy, combining proper low-bass extension with clear mids and an airy treble that avoids becoming unnecessarily aggressive.
At just 237g, with reduced clamping force and soft synthetic-velour earpads, they are also exceptionally easy to wear for long sessions. Add the 150-ohm impedance, replaceable parts and compatibility with Sennheiser's HD 500-series cables and boom microphone, and the HD 550 are equally at home with music, films, gaming and a dedicated headphone system.
Important: Fully Open-Back Headphones
The HD 550 are designed to let air and sound pass freely through their earcups. This helps create their spacious and natural presentation, but it also means they provide very little isolation from outside noise and will leak sound into the room. They are best suited to quiet home listening rather than commuting or use where other people nearby need silence.
Sennheiser HD 550 Open-Back Headphones
The Sennheiser HD 550 are lightweight open-back hi-fi headphones designed to combine detailed, neutral sound with the comfort required for genuinely long listening sessions.
At their heart is a custom 38mm dynamic transducer manufactured at Sennheiser's audiophile production facility in Tullamore, Ireland. The drivers are angled back towards the ears to help recreate the way sound naturally arrives from loudspeakers positioned in front of the listener, contributing to the HD 550's broad and precise stereo image.
With a 150-ohm impedance, wide 6Hz to 39.5kHz frequency response and distortion below 0.2%, the HD 550 are revealing enough for serious music listening while remaining compatible with a broad range of headphone amplifiers and hi-fi equipment.
- Open-back around-ear hi-fi headphones
- Custom 38mm dynamic transducers
- Transducers manufactured in Tullamore, Ireland
- Angled driver arrangement
- 6Hz to 39.5kHz frequency response
- 150-ohm impedance
- 106.7dB SPL at 1V RMS
- Less than 0.2% THD
- Wide and precise stereo soundstage
- Neutral, balanced tuning
- Extended sub-bass response
- High-grade metal-mesh earcup covers
- Acoustically transparent driver protection
- Reduced clamping force
- Synthetic-velour earpads
- Soft padded headband
- 237g headphone weight
- Detachable 1.8m cable
- 3.5mm stereo plug
- 6.35mm screw-on adapter supplied
- Replaceable cables and earpads
- Compatible with HD 500-series accessories
- Compatible with optional HD 500 BAM boom microphone
- Drawstring storage bag supplied
Custom 38mm Transducers
The HD 550 use custom 38mm dynamic transducers developed specifically for the model.
Sennheiser manufactures the drivers at its specialist audiophile production facility in Tullamore, Ireland, where careful production control helps maintain consistent performance and channel matching.
The transducers have been tuned to combine revealing detail with a smooth enough balance for extended everyday listening.
Angled Driver Positioning
The transducers are not mounted completely flat against the sides of the listener's head.
Instead, they are angled back towards the ears, helping sound arrive from a direction closer to the way we experience loudspeakers in a room.
This contributes to the HD 550's sense of:
- Width
- Depth
- Image placement
- Instrument separation
- Spatial awareness
Fully Open-Back Design
The rear of each earcup is deliberately open rather than sealed.
Sennheiser uses a high-grade metal mesh to protect the transducers while placing as little acoustic obstruction as possible between the rear of the driver and the surrounding air.
This helps reduce the enclosed reflections associated with closed-back headphones and allows the soundstage to feel more expansive and natural.
Why Open-Back Headphones?
Allowing the rear of the driver to breathe changes the way the headphone interacts with the listener and the surrounding air.
Typical benefits can include:
- More spacious stereo imaging
- Greater sense of air around instruments
- Natural reproduction of recording ambience
- Less enclosed presentation
- Improved positional information
Open or Closed-Back?
Open-back headphones such as the HD 550 are usually at their best in a quiet room where sound quality and spaciousness matter more than isolation. Closed-back headphones reduce leakage and outside noise, making them better suited to travel, offices and shared environments. You can read more in our Audio T guide to open and closed-back headphones.
6Hz to 39.5kHz Frequency Response
Sennheiser specifies the HD 550 from 6Hz to 39.5kHz.
The extremely low quoted extension does not mean every recording contains meaningful information at 6Hz, or that the listener consciously hears frequencies that low. What matters more is that the driver has been engineered to maintain controlled bass reproduction comfortably through the audible range.
Extended Sub-Bass
The HD 550 build on the HD 500-series platform with greater emphasis on properly extended low frequencies.
Rather than relying on an exaggerated mid-bass hump to create an immediate impression of weight, the intention is to retain useful energy further into the lowest frequencies while keeping the midrange clear.
This is particularly useful with:
- Electronic music
- Modern pop
- Film scores
- Orchestral percussion
- Organ recordings
- Low synthesiser and bass-guitar notes
Balanced Midrange
The midrange is where voices and a large proportion of acoustic instruments live.
The HD 550 have been tuned to keep this region relatively neutral rather than recessing voices between exaggerated bass and treble.
That makes them particularly useful for listeners who value believable vocal tone, acoustic instruments and the ability to follow individual parts within a busy mix.
Detailed but Controlled Treble
The HD 550 are designed to retain plenty of high-frequency information without relying on excessive brightness simply to sound detailed.
This helps cymbals, reverberation, acoustic space and transient detail remain clear while keeping the overall presentation suitable for long listening sessions.
150-Ohm Impedance
The HD 550 have a nominal impedance of 150 ohms.
This places them between low-impedance portable headphones and high-impedance models such as the 300-ohm HD 600.
They can therefore work with a wide variety of headphone outputs while still benefiting from better amplification as the rest of the system improves.
Do I Need a Headphone Amplifier?
Not necessarily. The HD 550 have been designed to work with a broad range of equipment. However, like most revealing hi-fi headphones, they can benefit from a good headphone amplifier, integrated amplifier or DAC/headphone amplifier with sufficient voltage and control.
106.7dB SPL Sensitivity
Sennheiser specifies a sound pressure level of 106.7dB at 1V RMS.
Combined with the 150-ohm impedance, this makes the HD 550 considerably less intimidating to drive than specification alone might initially suggest.
Low Distortion
Total harmonic distortion is specified below 0.2% at 1kHz and 90dB SPL.
Keeping distortion low allows subtle information within the recording to remain audible rather than being obscured by unwanted additional harmonics generated by the headphone itself.
Only 237g
The HD 550 weigh approximately 237g without the cable.
That is particularly light for a full-sized around-ear hi-fi headphone and helps reduce fatigue during longer sessions.
Lower weight also means the headband does not need excessive clamping force simply to keep the headphones securely in place.
Reduced Clamping Force
Sennheiser specifically revised the HD 550 fit to provide less clamping pressure than several other members of the HD 500 family.
This is especially useful for listeners who regularly spend several hours at a time listening, gaming or working at a computer.
Synthetic-Velour Earpads
The soft around-ear pads use synthetic velour-style material selected for both comfort and acoustic behaviour.
The open earcups also allow more airflow around the ears than a heavily sealed closed-back design, helping reduce heat build-up during longer sessions.
Soft Padded Headband
The revised headband combines a soft-touch outer material with compliant padding.
Alongside the low overall weight and reduced clamping pressure, this helps distribute the load comfortably across the head rather than concentrating pressure in one small area.
Modular HD 500-Series Construction
The HD 550 continue Sennheiser's modular approach to the HD 500 family.
Cables and earpads can be replaced, helping extend the useful life of the headphones and allowing different accessories to be fitted as requirements change.
This is particularly worthwhile with a passive wired headphone, where there is no rechargeable battery or wireless electronics imposing an obvious technological lifespan.
Detachable 1.8m Cable
A detachable 1.8m cable is supplied as standard.
The source end terminates in a conventional 3.5mm stereo jack, while a screw-on 6.35mm adapter is included for full-sized headphone outputs.
The length is practical for both desktop and traditional hi-fi use without leaving an excessive amount of cable on the floor.
3.5mm and 6.35mm Connections
The standard 3.5mm connection allows the HD 550 to work with a broad range of headphone sources.
The supplied 6.35mm adapter adds compatibility with equipment such as:
- Integrated amplifiers
- Dedicated headphone amplifiers
- DAC/headphone amplifiers
- AV receivers
- Audio interfaces
- Professional headphone outputs
Optional Balanced Cable
Sennheiser's HD 500 accessory range includes an optional balanced cable for compatible headphones including the HD 550.
This provides additional connection flexibility if your headphone amplifier offers a suitable balanced output.
A balanced connection is not automatically better simply because it is balanced; the quality of the amplifier itself remains more important.
Microphone-Ready Design
The HD 550 can also be converted into a high-quality wired headset using Sennheiser's optional HD 500 BAM boom-arm microphone.
The accessory replaces the standard headphone cable and incorporates a dedicated 10mm condenser microphone, inline volume control and microphone mute function.
This allows the same pair of HD 550 to move between serious music listening and communication without attaching a separate microphone to the earcup.
Useful for Gaming
The open soundstage and precise positional information make the HD 550 particularly interesting for gaming.
Unlike a wireless gaming headset, the passive wired connection introduces no Bluetooth codec delay and requires no battery.
With the optional HD 500 BAM microphone, the HD 550 can become a complete wired gaming headset while retaining their hi-fi headphone performance.
Useful for Films
A wide stereo image can make film and television soundtracks feel considerably more spacious through headphones.
The extended bass response also helps provide more weight to effects and film scores than an overly lean analytical headphone might deliver.
Useful for Remote Work
The 237g weight and relatively gentle clamping force make the HD 550 comfortable enough for extended computer use.
Add the optional boom microphone and the same headphones can be used for video meetings and calls.
Useful for Critical Music Listening
The balanced tuning and revealing nature of the HD 550 make them useful when you want to hear differences between recordings, sources and mastering choices.
They are sufficiently analytical to expose detail while deliberately avoiding a sound intended purely as a technical monitoring tool.
HD 550 or HD 560S?
HD 550
- Open-back around-ear design
- Custom 38mm transducers
- 150-ohm impedance
- 6Hz to 39.5kHz response
- 106.7dB SPL at 1V
- Less than 0.2% THD
- 237g
- Reduced clamping force
- Extended sub-bass
- Balanced, smooth overall tuning
- 1.8m cable
- HD 500 BAM microphone compatible
- Music and gaming all-rounder
HD 560S
- Open-back around-ear design
- Polymer-blend dynamic transducers
- 120-ohm impedance
- 6Hz to 38kHz response
- 110dB SPL at 1V
- Less than 0.05% THD
- 280g
- Highly analytical tuning
- Strong focus on reference accuracy
- 1.8m cable
- HD 500 BAM microphone compatible
- Particularly suited to critical A/B listening
Which Should You Choose?
The HD 560S remain an excellent choice if your main priority is analytical reference listening and comparing equipment, recordings or mixes.
The HD 550 take a slightly broader approach. They remain detailed and neutral enough for serious hi-fi listening, but combine this with lower weight, reduced clamping force, extended sub-bass and a smooth enough presentation for music, films and gaming alike.
There is therefore genuine reason to hear both rather than treating one as a straightforward replacement for the other.
HD 550 or HD 599?
The HD 550 use the familiar HD 500-series architecture but introduce a newer acoustic approach than the established HD 599.
Both use open 38mm dynamic drivers and are designed around comfort and spacious presentation, but the HD 550 offer greater quoted low-frequency extension, higher impedance and a more neutral, analytical balance.
The HD 599 remain appealing if you prefer their warmer presentation and traditional HD 500-series voicing.
A Strong First Step Into Serious Headphones
The HD 550 sit at a useful point where a headphone begins to reveal substantially more of the system without automatically requiring an expensive dedicated amplifier.
This makes them particularly suitable for somebody moving from conventional consumer headphones into a more serious hi-fi setup.
They Can Scale With Better Equipment
Although they do not need flagship amplification simply to work properly, the HD 550 are revealing enough to benefit as the source and headphone amplifier improve.
This means they can remain relevant if you later upgrade from a basic headphone output to a dedicated DAC or headphone amplifier.
No Batteries, Bluetooth or Apps
The HD 550 are entirely passive wired headphones.
There is no rechargeable battery to age, wireless codec to become obsolete, app required for setup or firmware to maintain.
Connect them to a suitable headphone output and they simply play whatever signal they are given.
Who Are the Sennheiser HD 550 For?
- Listeners wanting open-back hi-fi headphones
- People taking their first step into serious headphone listening
- Listeners wanting a wide soundstage
- People who value accurate instrument placement
- Music listeners wanting extended bass without excessive boom
- Listeners wanting a relatively neutral tonal balance
- Gaming systems
- Film and television listening
- Remote-working systems
- Desktop DAC and headphone-amplifier systems
- Traditional hi-fi systems with a headphone output
- Listeners wanting lightweight headphones for long sessions
- People wanting replaceable cables and earpads
- Users interested in adding the HD 500 BAM microphone later
Who Are They Not For?
- Commuters needing strong noise isolation
- Listeners wanting Active Noise Cancellation
- People wanting Bluetooth headphones
- Anyone listening beside somebody who requires silence
- Very noisy environments
- Listeners wanting a completely sealed, intimate headphone presentation
- Customers needing a microphone included as standard
Key Features
- Sennheiser HD 550
- SKU 700455
- Open-back hi-fi headphones
- Over-ear / circumaural fit
- Dynamic transducer principle
- Custom 38mm drivers
- Drivers manufactured in Ireland
- Angled transducers
- Wide stereo soundstage
- 6Hz to 39.5kHz frequency response
- 150-ohm nominal impedance
- 106.7dB SPL at 1V RMS
- Less than 0.2% THD
- Extended sub-bass performance
- Neutral midrange
- Detailed treble
- High-grade metal earcup mesh
- Acoustically transparent dust protection
- Reduced clamping force
- Synthetic-velour earpads
- Soft padded headband
- 237g headphone weight
- Detachable cable
- 1.8m cable length
- 3.5mm stereo jack plug
- 6.35mm screw-on adapter supplied
- Replaceable earpads
- Replaceable cable
- Modular HD 500-series construction
- Balanced cable available separately
- HD 500 BAM microphone compatible
- Drawstring storage bag supplied
- No Bluetooth
- No battery
- No Active Noise Cancellation
- No app required
Frequently Asked Questions
Are the Sennheiser HD 550 still current?
Yes. The HD 550 remain part of Sennheiser's current wired and audiophile headphone ranges.
Are the HD 550 open-back?
Yes. They use a fully open acoustic design with high-grade metal-mesh earcup covers.
Do the HD 550 block outside noise?
Very little. Open-back headphones deliberately provide minimal isolation from surrounding sound.
Can other people hear what I am listening to?
Yes. The open earcups allow sound to escape into the room, particularly at higher listening levels.
What size drivers do they use?
The HD 550 use custom 38mm dynamic transducers.
Where are the HD 550 drivers made?
Sennheiser manufactures the custom transducers at its audiophile production facility in Tullamore, Ireland.
Are the drivers angled?
Yes. They are angled towards the ears to help create a wide and natural stereo soundstage.
What is the frequency response?
6Hz to 39.5kHz.
What impedance are the HD 550?
150 ohms.
How sensitive are they?
Sennheiser specifies 106.7dB SPL at 1V RMS.
What is the total harmonic distortion?
Less than 0.2% at 1kHz and 90dB SPL.
Do I need a headphone amplifier?
Not necessarily. The HD 550 are designed to work with a broad range of suitable headphone outputs, although a good dedicated amplifier or DAC/headphone amplifier can allow them to perform closer to their potential.
Can I use them with an integrated amplifier?
Yes, provided the amplifier has a suitable headphone output.
Can I use them with a computer?
Yes, with a suitable headphone output, DAC or audio interface capable of driving 150-ohm headphones to the required level.
Can I use them with a phone?
Potentially, although many modern phones require an external USB-C or Lightning headphone adapter. Output capability varies considerably between adapters.
What connector do they use?
The supplied cable terminates in a 3.5mm stereo jack.
Is a 6.35mm adapter included?
Yes. A screw-on 3.5mm to 6.35mm adapter is supplied.
How long is the cable?
Approximately 1.8 metres.
Is the cable detachable?
Yes.
Can I use a balanced cable?
Sennheiser offers a compatible balanced HD 500-series cable separately for suitable headphones and amplifiers.
Can the earpads be replaced?
Yes. The HD 550 use Sennheiser's modular HD 500-series construction and compatible replacement earpads are available.
What are the earpads made from?
Sennheiser specifies synthetic velour.
How much do the HD 550 weigh?
Approximately 237g without the cable.
Are the HD 550 comfortable for long listening sessions?
Sennheiser specifically reduced the clamping force compared with several other HD 500-series models and combines the low 237g weight with soft earpads and headband padding.
Do the HD 550 have a microphone?
No microphone is supplied as standard.
Can I add a microphone?
Yes. Sennheiser's optional HD 500 BAM boom microphone is specifically compatible with the HD 550.
Are the HD 550 good for gaming?
Yes. Their open soundstage and precise positional imaging are useful for gaming, while the wired connection introduces no Bluetooth audio latency. The optional HD 500 BAM can add headset microphone functionality.
Are they good for films?
Yes. The open soundstage and extended low-frequency response suit films and television particularly well when listening in a quiet environment.
Are they suitable for commuting?
No. Their open-back design provides very little isolation and leaks sound to people nearby.
Do they have Bluetooth?
No. They are passive wired headphones.
Do they have Active Noise Cancellation?
No.
Do they need charging?
No. There is no battery.
What is the difference between HD 550 and HD 560S?
Both are open-back hi-fi headphones. The HD 560S place particularly strong emphasis on analytical reference accuracy, while the HD 550 combine detailed neutral sound with lower weight, reduced clamping pressure, extended sub-bass and a broader music, film and gaming focus.
What is the difference between HD 550 and HD 599?
The HD 550 use a newer 150-ohm transducer design with greater quoted bass extension and a more neutral analytical balance. The HD 599 are 50-ohm open-back headphones with a warmer presentation and the familiar traditional HD 500-series character.
What comes in the box?
The HD 550 are supplied with a 1.8m cable with 3.5mm plug, screw-on 6.35mm adapter and drawstring storage bag.
Related Sennheiser Products and Audio T Guides
Why Buy the Sennheiser HD 550 From Audio T?
Headphone specifications only tell part of the story. Comfort, tonal balance, amplifier matching and whether an open-back design suits your listening environment can all make a bigger difference than simply choosing the model with the widest quoted frequency response.
Audio T can help you compare the HD 550 with alternatives such as the HD 560S, HD 599 and HD 600, as well as advise on headphone amplifiers, DACs and the best way to connect them to your existing system.
- Friendly headphone advice
- HD 500-series comparisons
- Open and closed-back headphone guidance
- Headphone amplifier matching
- DAC and headphone amplifier advice
- 150-ohm headphone guidance
- Hi-fi system matching
- Gaming headphone advice
- HD 500 BAM compatibility guidance
- Headphone demonstrations where available
- Replacement cable and earpad advice
- Ongoing after-sales support
Contact your local Audio T store if you would like to arrange a demonstration or discuss whether the Sennheiser HD 550 are the right headphones for your system.