HEADPHONES · YOUR NEXT FACE-OFF

Sennheiser HD 400 PRO vs Sennheiser HD 505

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

WHAT DIFFERS

Rated total harmonic distortion<0.05% at 1 kHz, 90 dB SPL<0.2% (1 kHz / 90 dB SPL)

Ear padsVelour; replaceableSynthetic velour

Rated frequency range6–38,000 Hz (−10 dB)12 Hz – 38.5 kHz

3 of 8 verified differences, in the order listed below. Not a rating.

See the 8 verified differences

THE CONTENDER

Sennheiser HD 505

700453 · Copper Edition (black with copper/bronze accents) · wired

Full product profile Official image

Exact model & source notes

The HD 505 (article 700453, sold as the Copper Edition) is a open-back around-ear headphone from Sennheiser's HD 500 family, with a 120-ohm dynamic transducer angled forward in the cup, high-grade metal mesh earcup covers, a detachable 1.8 m cable with a 3.5 mm plug and a rated 237 g without the cable. Sennheiser describes its response as very close to the Harman Curve and as extending further into sub-bass than the HD 599.

Specifications checked 26 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 505 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 SIDE7 topics

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

SELECTED TOPIC

01 / 07

Open-back design

Open-back earcups are not sealed. Start here if your listening space is quiet; this construction is not a sound-quality rating.

Sennheiser HD 400 PRO: open-back · illustration, not to scale

Sennheiser HD 505: open-back · illustration, not to scale

Sennheiser HD 400 PROYes

Open-back. Manufacturer specification

Source 1 Source 2

Sennheiser HD 505Yes

Open-back. Manufacturer specification

Source 1

Choose your must-haves

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 ↓

8 verified differences, most decision-relevant first. 1 feature is the same under different published names, grouped below. 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 505Wired analogue; detachable 1.80 m cable with 3.5 mm plug (left-side entry) and supplied 3.5-to-6.35 mm screw-on 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 505

Manufacturer specification

Sennheiser HD 505 — 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 505Dynamic transducer, angled forward in the ear cups

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 505

Manufacturer specification

Sennheiser HD 505 — official UK product page and specifications

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

Rated total harmonic distortion

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

Sennheiser HD 505<0.2% (1 kHz / 90 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 505

Manufacturer specification · Rated at 1 kHz and 90 dB SPL; other models use different test levels, so compare with care.

Sennheiser HD 505 — 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.

Ear pads

Sennheiser HD 400 PROVelour; replaceable

Sennheiser HD 505Synthetic velour

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 505

Manufacturer specification

Sennheiser HD 505 — official UK product page and specifications

Check the exact configuration and source conditions for your use.

Rated frequency range

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

Sennheiser HD 50512 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 505

Manufacturer specification · No tolerance is stated.

Sennheiser HD 505 — 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 505Headphones, 1.80 m cable with 3.5 mm plug, 3.5-to-6.35 mm screw-on adapter, drawstring bag

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 505

Manufacturer specification

Sennheiser HD 505 — official UK product page and specifications

Check the exact configuration and source conditions for your use.

Show 2 more verified differences

Voltage-referenced sound pressure level

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

Sennheiser HD 505107.9 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 505

Manufacturer specification · Voltage reference (dB/V), not dB/mW.

Sennheiser HD 505 — 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.

Serviceability

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

Sennheiser HD 505HD 500-series cables and accessories are compatible; replacement parts such as ear cushions are offered

Sources

Sennheiser HD 400 PRO

Manufacturer specification

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

Sennheiser HD 505

Manufacturer specification

Sennheiser HD 505 — official UK product page and specifications

Check the exact configuration and source conditions for your use.

Same feature, different names (1)

The sources publish different names for the same feature. Both names and their sources are shown; they are not counted as differences.

Wearing style

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

Sennheiser HD 505Over-ear (circumaural), open-back dynamic 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 505

Manufacturer specification

Sennheiser HD 505 — official UK product page and specifications

Both sources state the same feature under different published names. This is not a verified difference; check the exact feature you need.

Small physical differences (1)

Weight

Sennheiser HD 400 PRO240 g

Sennheiser HD 505237 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 505

Manufacturer specification · Without the cable.

Sennheiser HD 505 — official UK product page and specifications

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

Missing or non-comparable evidence (11)

Active noise cancellation

Sennheiser HD 400 PRONot verified

Sennheiser HD 505Not verified

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 505

The reviewed exact sources do not explicitly establish active noise cancellation absence. Preserve separately sourced acoustic design and passive attenuation; they cannot turn omitted ANC into a false capability. · Manufacturer specification

Sennheiser HD 505 — 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 505Not 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 505

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 505 — 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 505Not 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 505

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 505 — official UK product page and specifications

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

Cable arrangement

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

Sennheiser HD 505Not verified

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 505

No source recorded for this side.

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 505Not 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 505

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 505Not 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 505

No source recorded for this side.

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

Frequency tuning

Sennheiser HD 400 PRONot verified

Sennheiser HD 505Response described as very close to the Harman Curve

Sources

Sennheiser HD 400 PRO

No source recorded for this side.

Sennheiser HD 505

Manufacturer specification · Sennheiser's description of its published HD 505 response graph; not a measurement by this site.

Sennheiser HD 505 — 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 505High-grade metal mesh earcup covers; revised synthetic leather headband

Sources

Sennheiser HD 400 PRO

No source recorded for this side.

Sennheiser HD 505

Manufacturer specification

Sennheiser HD 505 — official UK product page and specifications Sennheiser UK store — HD 505 product variant data (SKU and EAN)

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 505Not 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 505

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 505Not 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 505

No source recorded for this side.

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

Manufacturer sub-bass claim

Sennheiser HD 400 PRONot verified

Sennheiser HD 505Extends further into sub-bass than the HD 599

Sources

Sennheiser HD 400 PRO

No source recorded for this side.

Sennheiser HD 505

Manufacturer specification

Sennheiser HD 505 — official UK product page and specifications

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

3 shared fields have 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 505

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 505

What it brings

Its 107.9 dB at 1 V rating and 120-ohm impedance are published together, so buyers can judge how much voltage a phone, computer or amplifier needs to supply.
Manufacturer source
The cable is detachable, HD 500-series cables and accessories are stated to fit, and replacement ear cushions are offered.
Manufacturer source
A 3.5 mm plug with a screw-on 6.35 mm adapter covers both portable and hi-fi headphone sockets.
Manufacturer source

What to check

It is an open-back design, and Sennheiser publishes no ambient-noise attenuation figure for it.
Manufacturer source
The supplied detachable cable is 1.8 m long, with a 3.5 mm plug and a screw-on 6.35 mm adapter.
Manufacturer source Manufacturer source
Sennheiser does not state the driver size or a tolerance for the frequency range.
Manufacturer source

COMPARE THE DETAILS

Full specifications

How we verify

Differences only

24 of 24 specifications Sources in each row

Source-backed specifications for Sennheiser HD 400 PRO and Sennheiser HD 505
Specification	Sennheiser HD 400 PRO	Sennheiser HD 505

Wearing style 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 505 Manufacturer specification Sennheiser HD 505 — official UK product page and specifications	Over-ear (circumaural), open-back wired studio headphones	Over-ear (circumaural), open-back dynamic 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 505 Manufacturer specification Sennheiser HD 505 — 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 505 Manufacturer specification · Without the cable. Sennheiser HD 505 — official UK product page and specifications	240 g	237 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 505 Manufacturer specification Sennheiser HD 505 — official UK product page and specifications	Velour; replaceable	Synthetic velour
ServiceabilityDifferent Sources Sennheiser HD 400 PRO Manufacturer specification Sennheiser HD 400 PRO (article 700047) — official UK product page and technical data Sennheiser HD 505 Manufacturer specification Sennheiser HD 505 — official UK product page and specifications	Replaceable ear pads and components; ear pads, coiled cable and straight cable listed as spare parts	HD 500-series cables and accessories are compatible; replacement parts such as ear cushions are offered
Construction Sources Sennheiser HD 400 PRO No source recorded. Sennheiser HD 505 Manufacturer specification Sennheiser HD 505 — official UK product page and specifications Sennheiser UK store — HD 505 product variant data (SKU and EAN)	Not provided	High-grade metal mesh earcup covers; revised synthetic leather 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 505 Manufacturer specification Sennheiser HD 505 — 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; detachable 1.80 m cable with 3.5 mm plug (left-side entry) and supplied 3.5-to-6.35 mm screw-on 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 505 No source recorded.	3.5 mm jack plug with 6.3 mm adapter	Not provided
Cable arrangement 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 505 No source recorded.	Detachable, single-sided cable; coiled 3 m and straight 1.8 m cables supplied	Not provided
Cable length 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 505 Manufacturer specification Sennheiser HD 505 — official UK product page and specifications	1.8 m	1.8 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 505 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 505 Manufacturer specification Sennheiser HD 505 — official UK product page and specifications	Angled 120-ohm dynamic transducers with a polymer-blend diaphragm	Dynamic transducer, angled forward in the ear cups
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 505 Manufacturer specification · No tolerance is stated. Sennheiser HD 505 — official UK product page and specifications	6–38,000 Hz (−10 dB)	12 Hz – 38.5 kHz
Nominal impedance 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 505 Manufacturer specification Sennheiser HD 505 — official UK product page and specifications	120 ohm	120 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 505 Manufacturer specification · Voltage reference (dB/V), not dB/mW. Sennheiser HD 505 — official UK product page and specifications	110 dB SPL (1 kHz, 1 Vrms)	107.9 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 505 Manufacturer specification · Rated at 1 kHz and 90 dB SPL; other models use different test levels, so compare with care. Sennheiser HD 505 — official UK product page and specifications	<0.05% at 1 kHz, 90 dB SPL	<0.2% (1 kHz / 90 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 505 No source recorded.	120 dB SPL	Not provided
Frequency tuning Sources Sennheiser HD 400 PRO No source recorded. Sennheiser HD 505 Manufacturer specification · Sennheiser's description of its published HD 505 response graph; not a measurement by this site. Sennheiser HD 505 — official UK product page and specifications	Not provided	Response described as very close to the Harman Curve
Manufacturer sub-bass claim Sources Sennheiser HD 400 PRO No source recorded. Sennheiser HD 505 Manufacturer specification Sennheiser HD 505 — official UK product page and specifications	Not provided	Extends further into sub-bass than the HD 599

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 505 Manufacturer specification Sennheiser HD 505 — 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	Headphones, 1.80 m cable with 3.5 mm plug, 3.5-to-6.35 mm screw-on adapter, drawstring bag

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 505 No source recorded.	−15 °C to +55 °C	Not provided

Show unverified (3)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 505 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 505 — official UK product page and specifications	Not listed by the manufacturer	Not listed by the manufacturer
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 505 The reviewed exact sources do not explicitly establish active noise cancellation absence. Preserve separately sourced acoustic design and passive attenuation; they cannot turn omitted ANC into a false capability. · Manufacturer specification Sennheiser HD 505 — 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 505 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 505 — official UK product page and specifications	Not listed by the manufacturer	Not listed by the manufacturer

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Sennheiser HD 490 PRO

Impedance: 130 Ω
Cable length: 1.8 m
Wearing style: Over-ear (circumaural), open-back wired studio headphones

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Sennheiser HD 550

Impedance: 150 Ω
Cable length: 1.8 m
Wearing style: Over-ear, open-back dynamic headphones

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Sennheiser HD 560S

Impedance: 120 Ω
Wearing style: Over-ear, open-back dynamic headphones
Wired / wireless connections: Wired analogue; detachable cable with a 3.5 mm and 6.3 mm plug/adapter pair (which end is the plug conflicts across Sennheiser's sources)

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Sennheiser HD 660S2

Impedance: 300 Ω
Cable length: 1.8 m
Wearing style: Over-ear (circumaural), open-back dynamic headphones

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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.