Audio T Verdict
Few headphones earn genuine reference status and then remain relevant for decades, but the Sennheiser HD 600 have managed exactly that. Their appeal is not based on wireless features, noise cancellation or exaggerated bass. Instead, they concentrate on getting the fundamentals right: natural tonal balance, excellent midrange clarity, low distortion and an open presentation that makes it remarkably easy to hear what the rest of a hi-fi system is doing.
The 300-ohm design deserves a decent headphone output, and the completely open earcups mean these are headphones for quiet listening rather than trains, offices or shared spaces. Put them on the end of a capable amplifier or headphone DAC at home, however, and the HD 600 remain a superb way of getting seriously revealing sound without spending anywhere near flagship-headphone money.
They are analytical enough to show differences between recordings and equipment, but not so aggressively detailed that enjoying the music becomes secondary. That combination is a large part of the reason the HD 600 remain a benchmark more than thirty years after the original design appeared.
Important: Fully Open-Back Headphones
The HD 600 deliberately allow sound to pass freely through the rear of the earcups. This helps create their spacious and natural presentation, but it also means they provide very little isolation from external noise and other people nearby will hear some of what you are listening to. They are designed primarily for quiet home listening rather than commuting or use in shared spaces.
Sennheiser HD 600 Open-Back Headphones
The Sennheiser HD 600 are reference-quality open-back headphones designed around accurate, transparent music reproduction rather than deliberately emphasising particular parts of the frequency range.
The acoustic system combines a 42mm driver assembly with a 38mm diaphragm, lightweight aluminium voice coil, acoustically transparent earcups and carefully controlled airflow. Each transducer is measured against tight production tolerances to maintain consistent performance between the left and right channels.
With a 300-ohm impedance, detachable 3m cable, circumaural velour-covered earpads and modular construction, the HD 600 are intended as long-term hi-fi headphones rather than a disposable personal-audio product.
- Reference open-back hi-fi headphones
- Dynamic transducer system
- 42mm driver assembly
- 38mm diaphragm
- Ultra-light aluminium voice coil
- Acoustically transparent open earcups
- Stainless-steel acoustic mesh
- 12Hz to 40,500Hz frequency response
- 300-ohm impedance
- 97dB SPL at 1V
- Less than 0.1% THD at 1kHz and 1V
- Detachable dual-sided cable
- 3m cable length
- 3.5mm stereo connection
- 6.3mm adapter supplied
- Circumaural around-ear design
- Soft velour-covered earpads
- 260g headphone weight
- Modular replaceable construction
- Assembled in Ireland
A Headphone Reference for Decades
The HD 600 have remained a reference point within Sennheiser's headphone range for decades.
Rather than continually reinventing them to follow changing trends, Sennheiser has retained the fundamental acoustic approach that made the design successful in the first place.
The objective remains straightforward: reproduce the signal fed into the headphones with as little unwanted colouration as practical.
Why Reference Headphones Matter
A reference headphone should not try to make every recording sound spectacular by adding excessive bass, treble or artificial spaciousness.
Instead, it should allow you to hear differences in:
- Recordings
- Mastering quality
- Sources
- DACs
- Headphone amplifiers
- Streaming quality
- Different editions of the same album
This makes the HD 600 equally relevant to somebody assessing a hi-fi system and somebody who simply wants to hear recordings without an obviously imposed tonal character.
Open-Back Acoustic Design
The HD 600 use acoustically transparent open earcups rather than sealing the rear of each driver inside a closed chamber.
Sound generated behind the diaphragm can therefore dissipate through the earcup instead of being trapped and reflected back towards the driver.
This gives the transducer more freedom to operate and helps create the open, spacious and unforced presentation associated with the HD 600.
Why Open-Back Headphones Sound Different
Opening the rear of a headphone changes the way the driver interacts with the air around it.
The audible result can include:
- A more spacious presentation
- More natural ambience
- Greater sense of air around instruments
- Less enclosed or pressurised sound
- Clearer perception of recording space
The trade-off is greatly reduced isolation in both directions.
42mm Driver System
Sennheiser describes the HD 600 transducer assembly as a 42mm driver using a 38mm diaphragm.
The diaphragm is responsible for converting the incoming electrical signal into the acoustic movement that reaches your ears.
Its size, mass, suspension and magnetic system all influence the speed, distortion and tonal behaviour of the headphones.
Ultra-Light Aluminium Voice Coils
The HD 600 use lightweight aluminium voice coils.
Reducing moving mass helps the diaphragm respond rapidly when the electrical signal changes, which is important when reproducing fine transient information such as:
- Drum attacks
- Plucked strings
- Piano notes
- Vocal articulation
- Room reverberation
- Small dynamic changes
Acoustic Silk Controls Airflow
Sennheiser uses a fine acoustic silk material within the transducer system to control airflow around the diaphragm.
This helps manage unwanted turbulence while allowing the driver to retain the open character fundamental to the HD 600 design.
Stainless-Steel Acoustic Mesh
The resonator structure incorporates stainless-steel mesh selected to provide consistent acoustic behaviour.
Consistency matters in a stereo headphone because even relatively small differences between the left and right channels can influence image placement and tonal balance.
Matched Left and Right Performance
Sennheiser measures the HD 600 transducers against tight performance standards across the frequency range.
Keeping the left and right channels closely controlled helps preserve:
- Centre-image focus
- Instrument placement
- Stereo balance
- Tonal consistency
- Low-level spatial information
12Hz to 40,500Hz Frequency Response
The current HD 600 specification gives a frequency response of 12Hz to 40,500Hz.
The fact that this extends beyond the conventionally quoted range of human hearing should not be interpreted as a requirement to hear ultrasonic frequencies.
More relevant is the driver's ability to reproduce the audible range without needing to work close to its mechanical limits throughout normal listening.
Natural Midrange Reproduction
The midrange is one of the reasons the HD 600 have developed such a strong reputation.
Voices, acoustic instruments, guitars, piano and much of the information responsible for recognising instrumental timbre all occupy this region.
The HD 600 aim to reproduce this material without artificially pushing vocals forward or hollowing out the middle frequencies to create a false impression of scale.
Controlled Rather Than Exaggerated Bass
The HD 600 are not designed around deliberately boosted low frequencies.
Their open construction also behaves differently from the sealed earcups used by many modern portable headphones.
If you are accustomed to strongly bass-enhanced wireless headphones, the HD 600 may initially sound leaner. Listen further and the emphasis becomes less about quantity and more about pitch definition, texture and how bass integrates with the rest of the recording.
Smooth, Informative Treble
High-frequency information is important for recognising attack, ambience and subtle recording detail.
The HD 600 aim to reveal that information without relying on an exaggerated high-frequency balance simply to create an immediate impression of detail.
300-Ohm Impedance
The HD 600 have a nominal impedance of 300 ohms.
This is considerably higher than many headphones designed primarily for direct use with smartphones and small portable devices.
A high impedance does not automatically make a headphone difficult to drive, but the quality and available voltage of the headphone output become important if you want sufficient level and dynamic headroom.
Do I Need a Headphone Amplifier?
Not necessarily just to make the HD 600 produce sound, but they are revealing 300-ohm hi-fi headphones and can benefit considerably from a capable headphone output. A good integrated amplifier, dedicated headphone amplifier or DAC/headphone amplifier can provide greater voltage headroom and allow the HD 600 to perform closer to their potential.
Why Amplifier Quality Matters
Headphones are loudspeakers in miniature and still depend on the amplifier driving them.
With the HD 600, differences in headphone amplification can affect:
- Available listening volume
- Dynamic headroom
- Bass control
- Low-level detail
- Stereo image
- Overall tonal composure
The neutral nature of the HD 600 also makes changes elsewhere in the system relatively easy to hear.
97dB SPL Sensitivity
Sennheiser specifies a sound pressure level of 97dB at 1V.
This specification should be considered alongside the 300-ohm impedance when assessing whether a particular headphone output is likely to provide enough usable level.
Low Distortion
Total harmonic distortion is specified below 0.1% at 1kHz and 1V.
Low distortion helps preserve subtle information within the recording rather than masking it with unwanted additional harmonics generated by the headphone itself.
Detachable 3m Cable
The HD 600 use a detachable dual-sided cable approximately three metres long.
That length is practical for traditional home hi-fi use where the amplifier may be several feet away from the listening chair.
The cable can also be replaced separately rather than making cable damage the end of the headphones.
Replaceable Cable Connections
Each earcup has its own detachable cable connection.
This modular approach is important for a headphone designed to remain in service for many years because cables are among the components most exposed to regular wear.
3.5mm and 6.3mm Connections
The current Sennheiser specification lists a 3.5mm stereo connector with an adapter supplied for 6.3mm headphone sockets.
This allows the HD 600 to connect to a wide range of equipment, including:
- Integrated amplifiers
- Dedicated headphone amplifiers
- DAC/headphone amplifiers
- AV receivers
- Desktop audio interfaces
- Portable players with suitable output capability
260g Headphone Weight
The current HD 600 weigh approximately 260g without the cable.
Keeping moving and structural mass sensible helps make long listening sessions more comfortable, particularly for headphones intended primarily for stationary home use.
Circumaural Around-Ear Fit
The earpads sit around rather than directly on the ears.
This spreads pressure over a larger area and avoids compressing the outer ear in the way smaller on-ear designs can.
Soft Velour-Covered Earpads
Sennheiser uses soft velour-style ear cushions rather than sealed synthetic-leather pads.
The breathable material complements the open-back design and helps reduce the warm, enclosed feeling that can develop during long sessions with heavily sealed headphones.
Replaceable Earpads
Earpads are wear items and naturally soften and compress after extended use.
The HD 600's modular construction allows the cushions to be replaced rather than requiring the complete headphone to be discarded.
Replacing heavily worn pads can also be acoustically worthwhile because significant changes in pad thickness can alter the relationship between the driver and ear.
Built for Long-Term Ownership
One of the HD 600's less glamorous but genuinely valuable characteristics is serviceability.
Many parts are modular and replacement parts remain available, helping keep an established pair of HD 600 in service long after shorter-lived electronic products may have become obsolete.
Assembled in Ireland
The current HD 600 are assembled at Sennheiser's production facility in Ireland.
Sennheiser applies tightly controlled manufacturing tolerances to the acoustic components so that one pair should remain representative of the intended HD 600 performance rather than varying significantly from another.
HD 600 or HD 650?
HD 600
- Open-back design
- 300-ohm impedance
- 42mm driver assembly
- 38mm diaphragm
- 12Hz to 40,500Hz response
- 97dB SPL at 1V
- Neutral reference-oriented balance
- Highly revealing midrange
- 3m detachable cable
- 260g
HD 650
- Open-back design
- 300-ohm impedance
- 42mm driver assembly
- 38mm diaphragm
- 10Hz to 41,000Hz response
- Slightly smoother, richer presentation
- Strong focus on long-term listening
- 3m detachable cable
- Closely related 600-series architecture
- Alternative flavour rather than simple replacement
Which Should You Choose?
The Sennheiser HD 650 and HD 600 share a great deal of design heritage, but they are not identical in presentation.
The HD 600 are usually the more obvious starting point if your priority is a neutral reference balance and the ability to hear clearly what is happening elsewhere in the system.
The HD 650 provide an alternative interpretation of the same open-back 600-series philosophy and are well worth comparing directly if possible.
HD 600 or HD 660S2?
HD 600
- Established reference model
- 300-ohm impedance
- 12Hz to 40,500Hz
- 97dB SPL at 1V
- Neutral tonal approach
- 3m cable
- 3.5mm / 6.3mm connection
- 260g
- Excellent system-analysis headphone
HD 660S2
- Newer 600-series model
- 300-ohm impedance
- 8Hz to 41,500Hz
- 104dB SPL at 1V
- Extended sub-bass response
- 1.8m cables
- 6.3mm and 4.4mm balanced cables
- 260g
- More connection flexibility
Why Step Up to the HD 660S2?
The HD 660S2 build on the established 600-series concept with revised transducers, greater sensitivity, extended sub-bass and a 4.4mm balanced cable supplied as standard.
The HD 600 remain particularly appealing if neutrality, familiarity and reference performance are the priorities rather than simply owning the newest model.
Suitable for Critical Listening
The HD 600 are sufficiently revealing to expose differences between recordings without depending on the acoustics of a listening room.
This makes them useful when checking:
- Recording quality
- Mastering differences
- Source equipment
- DACs
- Headphone amplifiers
- Streaming settings
- File quality
Suitable for Serious Music Listening
Being a reference headphone does not mean the HD 600 are intended only as a technical tool.
The natural tonal balance, open construction and comfortable fit are equally useful when the objective is simply to sit down and listen through an album without distractions.
Ideal for Quiet Home Listening
The HD 600 make most sense in a quiet room where their open construction becomes an advantage rather than a limitation.
They are particularly well suited to:
- Dedicated hi-fi listening
- Late-evening listening where leakage will not disturb somebody nearby
- Home offices
- Listening rooms
- Desktop headphone systems
- Comparing hi-fi equipment
Not Designed for Portable Isolation
The HD 600 have no noise cancellation, no Bluetooth and virtually no passive isolation from their surroundings.
That is deliberate.
They are intended to optimise acoustic performance in a suitable environment rather than compromise the open design to make them more convenient on a train or aircraft.
No Batteries, Apps or Firmware
The HD 600 are entirely passive wired headphones.
There is no battery to age, no wireless codec to become obsolete, no app required for setup and no digital signal processing permanently altering the incoming signal.
The character of the system is therefore determined by the headphones themselves and the equipment driving them.
Who Are the Sennheiser HD 600 For?
- Listeners wanting neutral open-back headphones
- Serious home hi-fi listening
- Customers building a dedicated headphone system
- Listeners wanting excellent vocal and midrange reproduction
- People comparing sources and headphone amplifiers
- Listeners who value tonal accuracy over exaggerated bass
- Owners of capable headphone amplifiers
- Desktop DAC/headphone amplifier systems
- Listeners wanting replaceable cables and earpads
- Customers looking for a proven long-term headphone design
Who Are They Not For?
- Commuters needing noise isolation
- Listeners wanting Active Noise Cancellation
- Anyone wanting wireless headphones
- People listening beside somebody who needs silence
- Very noisy environments
- Listeners specifically wanting heavily boosted bass
- Customers who need a headset microphone
- People wanting a compact folding travel headphone
Key Features
- Sennheiser HD 600
- Reference hi-fi headphones
- Dynamic transducer principle
- Open-back construction
- Circumaural around-ear fit
- 42mm driver assembly
- 38mm diaphragm
- Ultra-light aluminium voice coil
- Acoustic silk airflow control
- Stainless-steel acoustic mesh
- 12Hz to 40,500Hz frequency response
- 300-ohm impedance
- 97dB SPL at 1V
- Less than 0.1% THD at 1kHz and 1V
- Closely controlled left/right performance
- Neutral reference-oriented tuning
- Open and spacious presentation
- Detachable dual-sided cable
- 3m cable length
- 3.5mm stereo connector
- 6.3mm adapter supplied
- Soft velour-covered earpads
- Replaceable earpads
- Replaceable cable
- Modular construction
- 260g headphone weight
- Assembled in Ireland
- Two-year manufacturer's warranty
- No Bluetooth
- No batteries
- No Active Noise Cancellation
- No app required
Frequently Asked Questions
Are the Sennheiser HD 600 still current?
Yes. The HD 600 remain part of Sennheiser's current wired, open-back and audiophile headphone ranges.
Are the HD 600 open-back?
Yes. The rear of each earcup is acoustically open to allow the driver to interact freely with the surrounding air.
Do the HD 600 block outside noise?
Very little. Their open-back design deliberately provides minimal isolation.
Can other people hear them?
Yes. Open-back headphones leak considerably more sound into the room than a sealed closed-back design.
What size drivers do the HD 600 use?
Sennheiser describes the HD 600 as using a 42mm driver assembly with a 38mm diaphragm.
What is the frequency response?
The current Sennheiser specification is 12Hz to 40,500Hz.
What impedance are the HD 600?
300 ohms.
How sensitive are they?
Sennheiser specifies 97dB SPL at 1V.
What is the THD?
Total harmonic distortion is specified below 0.1% at 1kHz and 1V.
Do I need a headphone amplifier?
A dedicated amplifier is not essential in every system, but the HD 600 are revealing 300-ohm headphones and benefit from a capable headphone output with sufficient voltage and headroom.
Can a phone drive the HD 600?
That depends entirely on the phone or external adapter being used. Many modern phones no longer have an analogue headphone output, and compact adapters vary considerably in output capability. A dedicated headphone DAC/amplifier is the safer option if you want to hear what the HD 600 can properly do.
Can I connect the HD 600 to an integrated amplifier?
Yes, provided the amplifier has a suitable headphone output.
Can I connect them to an AV receiver?
Yes. The supplied adapter allows connection to conventional 6.3mm headphone sockets.
What plug do the current HD 600 use?
Sennheiser's current specification lists a 3.5mm stereo connector and includes an adapter for 6.3mm sockets.
How long is the cable?
Approximately three metres.
Is the cable detachable?
Yes. It connects independently to the left and right earcups.
Can I replace the cable?
Yes. The modular construction allows the cable to be replaced separately.
Can the earpads be replaced?
Yes. Replacement ear cushions are available as wear items.
What are the earpads made from?
Sennheiser describes the current pads as soft cotton velveteen / velour-style material designed for extended listening comfort.
How much do the HD 600 weigh?
Approximately 260g without the cable.
Where are the HD 600 made?
Current HD 600 headphones are assembled at Sennheiser's production facility in Ireland.
Are the HD 600 good for classical music?
Their open presentation, natural tonal balance and strong midrange resolution make them particularly well suited to recordings where instrumental timbre and acoustic space matter.
Are they good for vocals?
Yes. Natural vocal reproduction is one of the longstanding strengths associated with the HD 600.
Are they bass-heavy?
No. The HD 600 are designed around a neutral reference presentation rather than deliberately boosted bass.
Are they suitable for gaming?
They can provide spacious and detailed game audio from a suitable headphone output, but they do not include a microphone and are not designed as a dedicated gaming headset.
Are they suitable for commuting?
No. Their open design provides little isolation and leaks sound, making them much better suited to quiet home listening.
Do the HD 600 have Bluetooth?
No. They are completely passive wired headphones.
Do they have noise cancellation?
No.
Do they need charging?
No. There is no battery.
What is the difference between HD 600 and HD 650?
Both are closely related 300-ohm open-back models. The HD 600 are generally positioned as the more neutral reference-oriented model, while the HD 650 offer an alternative balance with a slightly smoother and richer presentation.
What is the difference between HD 600 and HD 660S2?
The HD 660S2 are a newer 300-ohm design with revised transducers, greater sensitivity, stronger sub-bass extension and both 6.3mm and 4.4mm balanced cables supplied. The HD 600 remain the established neutral reference within the family.
Are spare parts still available?
Yes. Sennheiser continues to provide service support and replacement parts for the HD 600.
How long is the manufacturer's warranty?
The HD 600 currently fall within Sennheiser's 24-month consumer product warranty category, subject to Sennheiser's applicable warranty terms and proof of purchase.
Related Sennheiser Products and Audio T Guides
Why Buy the Sennheiser HD 600 From Audio T?
The HD 600 are revealing enough that the equipment driving them genuinely matters. Audio T can help you compare them with the HD 650, HD 660S2 and other hi-fi headphones, as well as advise on whether your existing amplifier or headphone output is suitable for a 300-ohm design.
We can also help with DAC and headphone-amplifier matching, demonstrations where available and choosing between open and closed-back headphones according to where and how you actually listen.
- Friendly headphone advice
- HD 600, HD 650 and HD 660S2 comparisons
- Open and closed-back headphone guidance
- Headphone amplifier matching
- DAC and headphone amplifier advice
- 300-ohm headphone guidance
- Hi-fi system matching
- Headphone demonstrations where available
- Replacement cable and earpad advice
- Long-term system upgrade guidance
- Ongoing after-sales support
Contact your local Audio T store if you would like to arrange a demonstration or discuss the best amplifier or source to partner with the Sennheiser HD 600.