HEADPHONES · YOUR NEXT FACE-OFF

Sennheiser HD 400 PRO vs Sennheiser HD 599

Real specs. Clear sources.Exact models · UK & US buying links

Compared products

YOUR FIRST CHOICE

Sennheiser HD 400 PRO

700047 · HD 400 PRO · wired

Full product profile Official image

Exact model & source notes

The HD 400 PRO (article 700047) is Sennheiser's open-back, around-ear wired studio headphone. It uses angled 120 Ω dynamic transducers with a polymer-blend diaphragm, velour ear pads and a detachable single-sided cable, and both a 3 m coiled and a 1.8 m straight cable come in the box. It weighs 240 g without the cable. Sennheiser lists a two-year warranty.

Specifications checked 27 Sept 2026.

Amazon links open search results. Check the exact variant, current price and availability with the retailer.

Manufacturer specifications

WHICH SUITS YOU?

Choose the HD 400 PRO for

Higher stated nominal impedance: 120 ohm vs 50 ohm

Choose the HD 599 for

Lower stated nominal impedance: 50 ohm vs 120 ohm
Longer stated cable length: 3 m vs 1.8 m

Built from verified specifications that differ. Not a rating or a recommendation.

See the 10 verified differences

THE CONTENDER

Sennheiser HD 599

506831 · Ivory · wired (not HD 599 SE)

Full product profile Official image

Exact model & source notes

The HD 599 (article 506831) is an open-back, over-ear wired headphone that Sennheiser describes as topping its 500 series, in an ivory finish with brown headband stitching. It has a 38 mm transducer with Sennheiser's E.A.R. (Ergonomic Acoustic Refinement) design, which Sennheiser says channels the audio signal directly into the ears, a 50 Ω impedance and soft replaceable ear pads, and comes with two cables — 3 m with a 6.3 mm plug and 1.2 m with a 3.5 mm plug. Sennheiser gives its weight as 250 g and explicitly lists active noise cancellation as False.

Specifications checked 27 Sept 2026.

Amazon links open search results. Check the exact variant, current price and availability with the retailer.

Manufacturer specifications

HD 400 PRO UK & US retailers

UK & US price history: no verified listing yet

HD 599 UK & US retailers

UK & US price history: no verified listing yet

Search links open retailer results, not a matched listing; eBay listings are checked daily. As an Amazon Associate I earn from qualifying purchases. As an eBay Partner, we may be compensated if you make a purchase.

THE DIFFERENCES, MADE VISIBLE

Visual facts

Differences first. Select a topic for its graphic, sources and conditions.

How to read this comparison

Manufacturer facts for the exact models shown. Not a quality rating or a test result.
“Different” means the known values differ, not that one is better.
Missing or conflicting evidence is marked and never counts as a difference. Source chips hold each fact’s sources and conditions.

FEATURES SIDE BY SIDE8 topics

Yes and No describe the listed feature. Missing evidence stays unverified.

SELECTED TOPIC

01 / 08

Impedance

Nominal electrical load, not sound quality or loudness. Output capability and headphone sensitivity matter together; impedance alone cannot decide whether an amplifier is needed.

Sennheiser HD 400 PRO120 Ω

Source 1 Source 2

Sennheiser HD 59950 Ω

Source 1

Explore the full specifications

Start with your listening environment. Open and closed earcups suit different surroundings. A closed back is not the same as active noise cancellation. Check the exact cable and headphone output. We do not turn impedance, driver size or unpaired lab results into a sound-quality score.

WHAT CHANGES BETWEEN THEM?

Key differences

Full specifications ↓

10 verified differences, most decision-relevant first. 2 are also drawn in Visual facts above. Missing information stays separate.

Wired / wireless connections

Sennheiser HD 400 PROWired; detachable single-sided cable: 3 m coiled cable with 3.5 mm jack plug and a 1.8 m straight cable supplied, plus a 3.5-to-6.3 mm adapter

Sennheiser HD 599Wired analogue; two cables supplied — 3 m with 6.3 mm straight plug and 1.2 m with 3.5 mm straight plug — plus a 6.3 mm to 3.5 mm adapter

Sources

Sennheiser HD 400 PRO

Manufacturer specification · Replacement coiled and straight cables are listed as spare parts.

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

Manufacturer specification

Sennheiser HD 599 — official UK product page and specifications

Check the exact configuration and source conditions for your use.

Nominal impedance

In Visual facts

Sennheiser HD 400 PRO120 ohm

Sennheiser HD 59950 ohm

Sources

Sennheiser HD 400 PRO

Manufacturer specification

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

Manufacturer specification

Sennheiser HD 599 — official UK product page and specifications

Check the exact configuration and source conditions for your use.

Driver construction

Sennheiser HD 400 PROAngled 120-ohm dynamic transducers with a polymer-blend diaphragm

Sennheiser HD 59938 mm transducer using Sennheiser’s proprietary transducer technology with the E.A.R. (Ergonomic Acoustic Refinement) design

Sources

Sennheiser HD 400 PRO

Manufacturer specification · Sennheiser does not state the transducer diameter on the pages and documents read.

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

Manufacturer specification · Sennheiser says the E.A.R. design channels the audio signal directly into the ears; the specification table gives the transducer size as 38 mm.

Sennheiser HD 599 — official UK product page and specifications Sennheiser UK store — HD 599 product variant data (SKU and EAN)

Check whether the diameter describes the complete transducer or only its diaphragm. Different labels and driver sizes do not establish better sound.

Cable arrangement

Sennheiser HD 400 PRODetachable, single-sided cable; coiled 3 m and straight 1.8 m cables supplied

Sennheiser HD 599Detachable; two cables supplied (3 m with 6.3 mm plug, 1.2 m with 3.5 mm plug)

Sources

Sennheiser HD 400 PRO

Manufacturer specification

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

Manufacturer specification · The specification table lists the cables as '1: 6.3mm 2: 3.5mm detachable'.

Sennheiser HD 599 — official UK product page and specifications

Check the exact configuration and source conditions for your use.

Cable length

In Visual facts

Sennheiser HD 400 PRO1.8 m

Sennheiser HD 5993 m

Sources

Sennheiser HD 400 PRO

Manufacturer specification · Supplied straight cable. A separate 3 m coiled cable is also supplied; the source does not specify whether its length is relaxed or extended.

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

Manufacturer specification · Longer of the two supplied cables (6.3 mm plug); the other is 1.2 m with a 3.5 mm plug.

Sennheiser HD 599 — official UK product page and specifications

Check the exact configuration and source conditions for your use.

Rated total harmonic distortion

Sennheiser HD 400 PRO<0.05% at 1 kHz, 90 dB SPL

Sennheiser HD 599<0.1% (1 kHz, 100 dB SPL)

Sources

Sennheiser HD 400 PRO

Manufacturer specification

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

Manufacturer specification

Sennheiser HD 599 — official UK product page and specifications

These published limits can use different input voltages, loudness levels and standards. They cannot establish lower distortion in matched listening conditions.

Show 4 more verified differences

Ear pads

Sennheiser HD 400 PROVelour; replaceable

Sennheiser HD 599Soft, replaceable ear pads on large ear cups

Sources

Sennheiser HD 400 PRO

Manufacturer specification

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

Manufacturer specification

Sennheiser HD 599 — official UK product page and specifications Sennheiser UK store — HD 599 product variant data (SKU and EAN)

Check the exact configuration and source conditions for your use.

Rated frequency range

Sennheiser HD 400 PRO6–38,000 Hz (−10 dB)

Sennheiser HD 59912 Hz – 38.5 kHz

Sources

Sennheiser HD 400 PRO

Manufacturer specification

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

Manufacturer specification · No tolerance is stated.

Sennheiser HD 599 — official UK product page and specifications

Range endpoints need their stated threshold. They do not describe response flatness or prove better bass, detail or sound quality.

In the box

Sennheiser HD 400 PROHD 400 PRO headphones, 3 m coiled cable with 3.5 mm jack plug, 3.5 mm to 6.3 mm adapter, 1.8 m straight cable, quick guide, safety guide

Sennheiser HD 599HD 599 headphones, 3 m cable with 6.3 mm straight plug, 1.2 m cable with 3.5 mm straight plug, 6.3 mm to 3.5 mm adapter

Sources

Sennheiser HD 400 PRO

Manufacturer specification

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

Manufacturer specification

Sennheiser HD 599 — official UK product page and specifications

Check the exact configuration and source conditions for your use.

Voltage-referenced sound pressure level

Sennheiser HD 400 PRO110 dB SPL (1 kHz, 1 Vrms)

Sennheiser HD 599106 dB SPL (1 kHz, 1 Vrms)

Sources

Sennheiser HD 400 PRO

Manufacturer specification · The specification sheet states 110 dB (1 kHz / 1 V RMS). The UK page technical table labels the same conditioned figure Max. sound pressure level; this record preserves the voltage-referenced claim without independently certifying a maximum. The separate 120 dB feature statement gives no reference and is not assumed to use these test conditions.

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

Manufacturer specification · Voltage reference (dB/V), not dB/mW; listed as 'Sound pressure level (SPL)'.

Sennheiser HD 599 — official UK product page and specifications

Keep the frequency and voltage or power reference attached. Sensitivity describes output for an input, not sound quality; dB/V and dB/mW are different measures.

Small physical differences (1)

Weight

Sennheiser HD 400 PRO240 g

Sennheiser HD 599250 g

Sources

Sennheiser HD 400 PRO

Manufacturer specification · Without cable, per the specification sheet and manual; the product page gives the same 240 g without stating a basis.

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)Sennheiser HD 400 PRO — instruction manual (09/2022)

Sennheiser HD 599

Manufacturer specification · Sennheiser does not say whether the figure includes the cable.

Sennheiser HD 599 — official UK product page and specifications

A size or weight trade-off; it does not establish the better product.

Configuration & compatibility details (1)

Wearing style

Sennheiser HD 400 PROOver-ear (circumaural), open-back wired studio headphones

Sennheiser HD 599Over-ear, open-back wired headphones

Sources

Sennheiser HD 400 PRO

Manufacturer specification

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

Manufacturer specification

Sennheiser HD 599 — official UK product page and specifications

Both sources describe the same wearing style and acoustic design in different words. The extra wording does not establish a different fit; compare the separately listed fields.

Missing or non-comparable evidence (10)

Active noise cancellation

Sennheiser HD 400 PRONot verified

Sennheiser HD 599No

Sources

Sennheiser HD 400 PRO

The complete exact sources establish an open dynamic wired design but do not explicitly negate active noise cancellation. Open construction and omission of ANC do not establish a false capability. · Manufacturer specification

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

Manufacturer specification · The specification table lists 'Active Noise Cancellation: False'; passive open-back headphones.

Sennheiser HD 599 — official UK product page and specifications

Evidence is missing or conflicting on at least one side. This is not a verified difference.

Microphone

In Visual facts

Sennheiser HD 400 PRONot verified

Sennheiser HD 599Not verified

Sources

Sennheiser HD 400 PRO

The complete exact sources list the headphone and accessories but do not explicitly establish absence of a microphone. An omitted microphone and a stereo headphone plug alone cannot become a sourced false capability. · Manufacturer specification

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

The reviewed exact sources do not explicitly establish microphone absence. Omission from a package or technical inventory, a stereo audio connector, and a without-remote statement do not establish microphone=false. · Manufacturer specification

Sennheiser HD 599 — official UK product page and specifications

Evidence is missing or conflicting on at least one side. This is not a verified difference.

Battery life

Sennheiser HD 400 PRONot verified

Sennheiser HD 599Not verified

Sources

Sennheiser HD 400 PRO

The retained exact sources do not explicitly establish battery life or that no battery is required for operation. Do not infer a not-applicable operating requirement from analogue/dynamic construction or a battery-included No row. · Manufacturer specification

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data

Sennheiser HD 599

The reviewed exact sources do not explicitly establish battery life or that no battery is required for operation. A wired/dynamic audio path, omitted charger or Battery included N is not an explicit operating-power requirement. · Manufacturer specification

Sennheiser HD 599 — official UK product page and specifications

Evidence is missing or conflicting on at least one side. This is not a verified difference.

Coiled cable rated length

Sennheiser HD 400 PRO3 m

Sennheiser HD 599Not verified

Sources

Sennheiser HD 400 PRO

Manufacturer specification · Separate supplied coiled cable. The source states 3 m but does not establish its relaxed/extended measurement basis. A 1.8 m straight cable is also supplied.

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

No source recorded for this side.

Evidence is missing or conflicting on at least one side. This is not a verified difference.

Supplied plug and adapter

Sennheiser HD 400 PRO3.5 mm jack plug with 6.3 mm adapter

Sennheiser HD 599Not verified

Sources

Sennheiser HD 400 PRO

Manufacturer specification

Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)Sennheiser HD 400 PRO — instruction manual (09/2022)

Sennheiser HD 599

No source recorded for this side.

Evidence is missing or conflicting on at least one side. This is not a verified difference.

Driver diameter

Sennheiser HD 400 PRONot verified

Sennheiser HD 59938 mm

Sources

Sennheiser HD 400 PRO

No source recorded for this side.

Sennheiser HD 599

Manufacturer specification

Sennheiser HD 599 — official UK product page and specifications

Evidence is missing or conflicting on at least one side. This is not a verified difference.

Construction

Sennheiser HD 400 PRONot verified

Sennheiser HD 599Ivory colour scheme with brown headband stitching and matte metallic detailing on the ear cups and headband

Sources

Sennheiser HD 400 PRO

No source recorded for this side.

Sennheiser HD 599

Manufacturer specification

Sennheiser HD 599 — official UK product page and specifications

Evidence is missing or conflicting on at least one side. This is not a verified difference.

Operating temperature

Sennheiser HD 400 PRO−15 °C to +55 °C

Sennheiser HD 599Not verified

Sources

Sennheiser HD 400 PRO

Manufacturer specification · Relative humidity up to 90%.

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)

Sennheiser HD 599

No source recorded for this side.

Evidence is missing or conflicting on at least one side. This is not a verified difference.

Serviceability

Sennheiser HD 400 PROReplaceable ear pads and components; ear pads, coiled cable and straight cable listed as spare parts

Sennheiser HD 599Not verified

Sources

Sennheiser HD 400 PRO

Manufacturer specification

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data

Sennheiser HD 599

No source recorded for this side.

Evidence is missing or conflicting on at least one side. This is not a verified difference.

Advertised SPL without stated reference

Sennheiser HD 400 PRO120 dB SPL

Sennheiser HD 599Not verified

Sources

Sennheiser HD 400 PRO

Manufacturer specification · UK page feature statement. Frequency, input voltage/power and measurement reference are not stated; the 120 dB claim is not labelled maximum. Do not compare it numerically with the specifically conditioned 110 dB at1 kHz/1 Vrms claim or use it as a comparable sensitivity/maximum-output input.

Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data

Sennheiser HD 599

No source recorded for this side.

Evidence is missing or conflicting on at least one side. This is not a verified difference.

1 shared field has the same recorded value.

YOUR HEADPHONES. YOUR RULES.

Check against your must-haves

Feature matching for the features you select. It doesn’t rate sound or comfort.

Start with your listening setup.

Choose a starting point, then fine-tune your must-haves.

FINE-TUNE THE DETAILS

Your essentials.

These shortcuts select the features shown above. Check the fit against your own equipment and listening space.

A feature match describes the selected requirements. It doesn’t rate sound or comfort.

Open-back designFor a quiet listening spaceClosed-back designAn enclosed outer earcupDetachable cableUnplug the cable at the headphonesBuilt-in microphoneFor calls and voice chatActive noise cancellationNot the same as a closed back

YOUR CHOICE

Sennheiser HD 400 PRO

Select a feature to check your fit.

YOUR CHOICE

Sennheiser HD 599

Select a feature to check your fit.

Feature matching, not a sound-quality score. The specification table links to the evidence for each feature.

WHAT EACH CHOICE ASKS OF YOU

What it brings and what to check

Sennheiser HD 400 PRO

What it brings

Two cables come in the box — a 3 m coiled cable and a 1.8 m straight cable — plus a 3.5-to-6.3 mm adapter, so desk and studio setups are covered without buying accessories.
Manufacturer source Manufacturer source
Angled 120-ohm dynamic transducers use a polymer-blend diaphragm, and the headphones weigh 240 g without the cable.
Manufacturer source Manufacturer source
Ear pads and both cable types are listed as replaceable spare parts.
Manufacturer source

What to check

It uses an open acoustic principle, and Sennheiser publishes no ambient-noise attenuation figure for it.
Manufacturer source Manufacturer source
The specification sheet gives 110 dB SPL at 1 kHz / 1 V RMS. A separate feature statement gives 120 dB SPL without a measurement reference, so the two figures cannot be treated as the same test. The transducer diameter is not stated.
Manufacturer source Manufacturer source
The supplied cables use a 3.5 mm plug, with a 6.3 mm adapter included in the box.
Manufacturer source Manufacturer source

Sennheiser HD 599

What it brings

Two cables are supplied — 3 m with a 6.3 mm straight plug and 1.2 m with a 3.5 mm straight plug — plus a 6.3 mm to 3.5 mm adapter.
Manufacturer source
Sennheiser publishes both the 50 Ω impedance and a 106 dB SPL at 1 V rating, which helps estimate how much output a source needs to drive it.
Manufacturer source
The large ear cups use soft ear pads that Sennheiser describes as replaceable.
Manufacturer source Manufacturer source

What to check

It is an open-back design, and Sennheiser publishes no ambient-noise attenuation figure for it.
Manufacturer source
Sennheiser does not say whether the 250 g weight includes a cable.
Manufacturer source

COMPARE THE DETAILS

Full specifications

How we verify

Differences only

23 of 23 specifications Sources in each row

Source-backed specifications for Sennheiser HD 400 PRO and Sennheiser HD 599
Specification	Sennheiser HD 400 PRO	Sennheiser HD 599

Wearing styleDifferent Sources Sennheiser HD 400 PRO Manufacturer specification Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 Manufacturer specification Sennheiser HD 599 — official UK product page and specifications	Over-ear (circumaural), open-back wired studio headphones	Over-ear, open-back wired headphones
Acoustic design Sources Sennheiser HD 400 PRO Manufacturer specification Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 Manufacturer specification Sennheiser HD 599 — official UK product page and specifications	Open-back	Open-back
WeightDifferent Sources Sennheiser HD 400 PRO Manufacturer specification · Without cable, per the specification sheet and manual; the product page gives the same 240 g without stating a basis. Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)Sennheiser HD 400 PRO — instruction manual (09/2022) Sennheiser HD 599 Manufacturer specification · Sennheiser does not say whether the figure includes the cable. Sennheiser HD 599 — official UK product page and specifications	240 g	250 g
Ear padsDifferent Sources Sennheiser HD 400 PRO Manufacturer specification Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 Manufacturer specification Sennheiser HD 599 — official UK product page and specifications Sennheiser UK store — HD 599 product variant data (SKU and EAN)	Velour; replaceable	Soft, replaceable ear pads on large ear cups
Serviceability Sources Sennheiser HD 400 PRO Manufacturer specification Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 599 No source recorded.	Replaceable ear pads and components; ear pads, coiled cable and straight cable listed as spare parts	Not provided
Construction Sources Sennheiser HD 400 PRO No source recorded. Sennheiser HD 599 Manufacturer specification Sennheiser HD 599 — official UK product page and specifications	Not provided	Ivory colour scheme with brown headband stitching and matte metallic detailing on the ear cups and headband

Wired / wireless connectionsDifferent Sources Sennheiser HD 400 PRO Manufacturer specification · Replacement coiled and straight cables are listed as spare parts. Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 Manufacturer specification Sennheiser HD 599 — official UK product page and specifications	Wired; detachable single-sided cable: 3 m coiled cable with 3.5 mm jack plug and a 1.8 m straight cable supplied, plus a 3.5-to-6.3 mm adapter	Wired analogue; two cables supplied — 3 m with 6.3 mm straight plug and 1.2 m with 3.5 mm straight plug — plus a 6.3 mm to 3.5 mm adapter
Supplied plug and adapter Sources Sennheiser HD 400 PRO Manufacturer specification Sennheiser HD 400 PRO — product specification sheet (EN, V1.0)Sennheiser HD 400 PRO — instruction manual (09/2022) Sennheiser HD 599 No source recorded.	3.5 mm jack plug with 6.3 mm adapter	Not provided
Cable arrangementDifferent Sources Sennheiser HD 400 PRO Manufacturer specification Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 Manufacturer specification · The specification table lists the cables as '1: 6.3mm 2: 3.5mm detachable'. Sennheiser HD 599 — official UK product page and specifications	Detachable, single-sided cable; coiled 3 m and straight 1.8 m cables supplied	Detachable; two cables supplied (3 m with 6.3 mm plug, 1.2 m with 3.5 mm plug)
Cable lengthDifferent Sources Sennheiser HD 400 PRO Manufacturer specification · Supplied straight cable. A separate 3 m coiled cable is also supplied; the source does not specify whether its length is relaxed or extended. Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 Manufacturer specification · Longer of the two supplied cables (6.3 mm plug); the other is 1.2 m with a 3.5 mm plug. Sennheiser HD 599 — official UK product page and specifications	1.8 m	3 m
Coiled cable rated length Sources Sennheiser HD 400 PRO Manufacturer specification · Separate supplied coiled cable. The source states 3 m but does not establish its relaxed/extended measurement basis. A 1.8 m straight cable is also supplied. Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 No source recorded.	3 m	Not provided

Driver constructionDifferent Sources Sennheiser HD 400 PRO Manufacturer specification · Sennheiser does not state the transducer diameter on the pages and documents read. Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 Manufacturer specification · Sennheiser says the E.A.R. design channels the audio signal directly into the ears; the specification table gives the transducer size as 38 mm. Sennheiser HD 599 — official UK product page and specifications Sennheiser UK store — HD 599 product variant data (SKU and EAN)	Angled 120-ohm dynamic transducers with a polymer-blend diaphragm	38 mm transducer using Sennheiser’s proprietary transducer technology with the E.A.R. (Ergonomic Acoustic Refinement) design
Rated frequency rangeDifferent Sources Sennheiser HD 400 PRO Manufacturer specification Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 Manufacturer specification · No tolerance is stated. Sennheiser HD 599 — official UK product page and specifications	6–38,000 Hz (−10 dB)	12 Hz – 38.5 kHz
Nominal impedanceDifferent Sources Sennheiser HD 400 PRO Manufacturer specification Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 Manufacturer specification Sennheiser HD 599 — official UK product page and specifications	120 ohm	50 ohm
Voltage-referenced sound pressure levelDifferent Sources Sennheiser HD 400 PRO Manufacturer specification · The specification sheet states 110 dB (1 kHz / 1 V RMS). The UK page technical table labels the same conditioned figure Max. sound pressure level; this record preserves the voltage-referenced claim without independently certifying a maximum. The separate 120 dB feature statement gives no reference and is not assumed to use these test conditions. Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 Manufacturer specification · Voltage reference (dB/V), not dB/mW; listed as 'Sound pressure level (SPL)'. Sennheiser HD 599 — official UK product page and specifications	110 dB SPL (1 kHz, 1 Vrms)	106 dB SPL (1 kHz, 1 Vrms)
Rated total harmonic distortionDifferent Sources Sennheiser HD 400 PRO Manufacturer specification Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 Manufacturer specification Sennheiser HD 599 — official UK product page and specifications	<0.05% at 1 kHz, 90 dB SPL	<0.1% (1 kHz, 100 dB SPL)
Advertised SPL without stated reference Sources Sennheiser HD 400 PRO Manufacturer specification · UK page feature statement. Frequency, input voltage/power and measurement reference are not stated; the 120 dB claim is not labelled maximum. Do not compare it numerically with the specifically conditioned 110 dB at1 kHz/1 Vrms claim or use it as a comparable sensitivity/maximum-output input. Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 599 No source recorded.	120 dB SPL	Not provided
Driver diameter Sources Sennheiser HD 400 PRO No source recorded. Sennheiser HD 599 Manufacturer specification Sennheiser HD 599 — official UK product page and specifications	Not provided	38 mm

Active noise cancellation Sources Sennheiser HD 400 PRO The complete exact sources establish an open dynamic wired design but do not explicitly negate active noise cancellation. Open construction and omission of ANC do not establish a false capability. · Manufacturer specification Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 Manufacturer specification · The specification table lists 'Active Noise Cancellation: False'; passive open-back headphones. Sennheiser HD 599 — official UK product page and specifications	Not listed by the manufacturer	No

In the boxDifferent Sources Sennheiser HD 400 PRO Manufacturer specification Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 Manufacturer specification Sennheiser HD 599 — official UK product page and specifications	HD 400 PRO headphones, 3 m coiled cable with 3.5 mm jack plug, 3.5 mm to 6.3 mm adapter, 1.8 m straight cable, quick guide, safety guide	HD 599 headphones, 3 m cable with 6.3 mm straight plug, 1.2 m cable with 3.5 mm straight plug, 6.3 mm to 3.5 mm adapter

Operating temperature Sources Sennheiser HD 400 PRO Manufacturer specification · Relative humidity up to 90%. Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 No source recorded.	−15 °C to +55 °C	Not provided

Show unverified (2)Not verified, not provided or conflicting for both products. Kept for completeness; never counted as a difference.

Specifications without verified values for either product
Microphone Sources Sennheiser HD 400 PRO The complete exact sources list the headphone and accessories but do not explicitly establish absence of a microphone. An omitted microphone and a stereo headphone plug alone cannot become a sourced false capability. · Manufacturer specification Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 400 PRO — product specification sheet (EN, V1.0) Sennheiser HD 599 The reviewed exact sources do not explicitly establish microphone absence. Omission from a package or technical inventory, a stereo audio connector, and a without-remote statement do not establish microphone=false. · Manufacturer specification Sennheiser HD 599 — official UK product page and specifications	Not listed by the manufacturer	Not listed by the manufacturer
Battery life Sources Sennheiser HD 400 PRO The retained exact sources do not explicitly establish battery life or that no battery is required for operation. Do not infer a not-applicable operating requirement from analogue/dynamic construction or a battery-included No row. · Manufacturer specification Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 599 The reviewed exact sources do not explicitly establish battery life or that no battery is required for operation. A wired/dynamic audio path, omitted charger or Battery included N is not an explicit operating-power requirement. · Manufacturer specification Sennheiser HD 599 — official UK product page and specifications	Not listed by the manufacturer	Not listed by the manufacturer

First product manufacturer source Second product manufacturer source

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Each record represents an explicitly checked model and configuration. Original import: 5 Sept 2026; this is not its verification date. This is not a list of current offers or a popularity ranking.