HEADPHONES · YOUR NEXT FACE-OFF

Beyerdynamic MMX 330 PRO vs Sennheiser HD 660S2

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

Compared products

YOUR FIRST CHOICE

Beyerdynamic MMX 330 PRO

1001163 · black · wired gaming headset (not MANUFAKTUR)

Full product profile Official image

Exact model & source notes

The MMX 330 PRO (article 1001163, black) is beyerdynamic's open-back, around-ear wired gaming headset and the open counterpart to the closed MMX 300 PRO. It uses the 48-ohm STELLAR.45 dynamic driver, a cardioid condenser boom microphone and a detachable single-sided 2.5 m cable with separate headphone and microphone plugs plus a console adapter. It weighs 318 g without the cable and has replaceable velour ear pads.

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 Beyerdynamic MMX 330 PRO for

Lower stated nominal impedance: 48 ohm vs 300 ohm
Longer stated cable length: 2.5 m vs 1.8 m

Choose the Sennheiser HD 660S2 for

Higher stated nominal impedance: 300 ohm vs 48 ohm

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

See the 11 verified differences

THE CONTENDER

Sennheiser HD 660S2

700240 · black with bronze accents · 300 ohm · 1.8 m balanced and unbalanced cables

Full product profile Official image

Exact model & source notes

The HD 660S2 is an open-back, over-ear headphone with a 38 mm dynamic driver rated 8–41,500 Hz (−10 dB) at 300 ohms. Sennheiser revised its acoustics for stronger sub-bass, and it ships with 1.8 m 6.35 mm unbalanced and 4.4 mm balanced cables plus a 3.5 mm adapter.

Specifications checked 11 Sept 2026.

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

Manufacturer specifications

Beyerdynamic MMX 330 PRO UK & US retailers

UK & US price history: no verified listing yet

Sennheiser HD 660S2 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.

Beyerdynamic MMX 330 PRO48 Ω

Source 1 Source 2

Sennheiser HD 660S2300 Ω

Manufacturer specification · Nominal impedance; check that your amplifier or audio source can drive this load.

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 ↓

11 verified differences, most decision-relevant first. 2 are also drawn in Visual facts above. 1 feature is the same under different published names, grouped below. Missing information stays separate.

Wired / wireless connections

Beyerdynamic MMX 330 PROWired; detachable single-sided 2.5 m cable ending in two 3.5 mm plugs (headphone and microphone), plus a supplied adapter to a single 3.5 mm combination jack

Sennheiser HD 660S2Wired analogue stereo; 1.8 m cables with 6.35 mm unbalanced and 4.4 mm balanced plugs; included 3.5 mm adapter

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification · The cable connects to the headset with a 5-pole jack plug.

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

Manufacturer specification

Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications

Check the exact configuration and source conditions for your use.

Nominal impedance

In Visual facts

Beyerdynamic MMX 330 PRO48 ohm

Sennheiser HD 660S2300 ohm

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

Manufacturer specification · Nominal impedance; check that your amplifier or audio source can drive this load.

Sennheiser HD 660S2 — operating guide and specifications

Check the exact configuration and source conditions for your use.

Driver construction

Beyerdynamic MMX 330 PRODynamic STELLAR.45 driver

Sennheiser HD 660S238 mm open dynamic transducer; aluminium voice coil and vented magnet system

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification · beyerdynamic's driver name; a diameter is not stated in the sources read.

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

Manufacturer specification · Sennheiser lists 38 mm as the transducer size.

Sennheiser HD 660S2 — exact model specifications

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

Cable arrangement

Beyerdynamic MMX 330 PRODetachable, single-sided straight cable

Sennheiser HD 660S2Detachable 1.8 m unbalanced and 4.4 mm balanced cables included; XLR-4 cable optional

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification

beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

Manufacturer specification · Optional cables are sold separately; balanced cables need a balanced headphone output.

Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications

Check the exact configuration and source conditions for your use.

Cable length

In Visual facts

Beyerdynamic MMX 330 PRO2.5 m

Sennheiser HD 660S21.8 m

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification

beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

Manufacturer specification · Length of the supplied cable.

Sennheiser HD 660S2 — operating guide and specifications

Check the exact configuration and source conditions for your use.

Supplied plugs and adapter

Beyerdynamic MMX 330 PRO2 × 3-pole 3.5 mm plugs (headphone / microphone); adapter from 2 × 3.5 mm sockets to 1 × 4-pole 3.5 mm plug

Sennheiser HD 660S26.35 mm unbalanced cable; 4.4 mm balanced cable; 6.35 mm-to-3.5 mm adapter

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification

beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

Manufacturer specification · The 4.4 mm balanced cable needs a balanced headphone output; an XLR-4 cable is optional.

Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications

Check the exact configuration and source conditions for your use.

Show 5 more verified differences

Rated total harmonic distortion

Beyerdynamic MMX 330 PRO<0.05% at 500 Hz

Sennheiser HD 660S2≤0.04% at 1 kHz, 100 dB SPL

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification

beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

Manufacturer specification · Rated at 1 kHz and 100 dB SPL; other models use different test levels, so compare with care.

Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications

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

Earpads

Beyerdynamic MMX 330 PROVelour, replaceable (spare part 1001656); headband pad also replaceable

Sennheiser HD 660S2Velour ear pads; replaceable

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification · beyerdynamic says MMX 300 PRO ear pads are not compatible with the MMX 330 PRO.

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

Manufacturer specification · Replacement procedure shown in the manual.

Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications

Check the exact configuration and source conditions for your use.

Rated frequency range

Beyerdynamic MMX 330 PRO5–40,000 Hz

Sennheiser HD 660S28–41,500 Hz (−10 dB)

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

Manufacturer specification

Sennheiser HD 660S2 — operating guide and specifications

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

Rated sensitivity

Beyerdynamic MMX 330 PRO96 dB SPL at 1 mW / 500 Hz

Sennheiser HD 660S2104 dB SPL at 1 kHz, 1 V rms

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

Manufacturer specification · Rated at 1 kHz with 1 V rms; not directly comparable with dB/mW ratings.

Sennheiser HD 660S2 — operating guide 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.

Weight without cable

Beyerdynamic MMX 330 PRO318 g

Sennheiser HD 660S2260 g

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification · The product pages state 318 g without cable; the spec sheet gives 318 g without stating the basis.

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

Manufacturer specification · Approximate, without the cable.

Sennheiser HD 660S2 — operating guide and specifications

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

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

Beyerdynamic MMX 330 PROOver-ear (circumaural), open-back wired gaming headset with boom microphone

Sennheiser HD 660S2Over-ear (circumaural), open-back dynamic headphones

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

Manufacturer specification

Sennheiser HD 660S2 — operating guide and specifications

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

Missing or non-comparable evidence (18)

Active noise cancellation

Beyerdynamic MMX 330 PRONo

Sennheiser HD 660S2Not verified

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification · Passive, open-back wired headset; no active noise cancellation is listed.

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

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 660S2 — operating guide and specifications

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

Microphone

In Visual facts

Beyerdynamic MMX 330 PROYes

Sennheiser HD 660S2Not verified

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification · Cardioid back-electret condenser boom microphone; boom approx. 190 mm.

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

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 660S2 — operating guide and specifications

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

Battery life

Beyerdynamic MMX 330 PRONot required: passive wired headset powered by the audio source

Sennheiser HD 660S2Not verified

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification · Passive headphones with no battery or charging; the condenser microphone takes its supply from the connected device's microphone input.

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

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 660S2 — operating guide and specifications

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

Published acoustic changes

Beyerdynamic MMX 330 PRONot verified

Sennheiser HD 660S2Revised 300-ohm coil, more compliant surround, 70 Hz resonance and revised transducer airflow

Sources

Beyerdynamic MMX 330 PRO

No source recorded for this side.

Sennheiser HD 660S2

Manufacturer specification · Sennheiser describes these changes as the S2 revision of the HD 660S.

Sennheiser HD 660S2 — exact model specifications

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

Rated contact pressure

Beyerdynamic MMX 330 PRONot verified

Sennheiser HD 660S2Approximately 6.0 N ±1.0 N

Sources

Beyerdynamic MMX 330 PRO

No source recorded for this side.

Sennheiser HD 660S2

Manufacturer specification · Nominal clamping force; individual fit and comfort can differ.

Sennheiser HD 660S2 — operating guide and specifications

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

Cable remote

Beyerdynamic MMX 330 PROConflicting evidence

Sennheiser HD 660S2Not verified

Sources

Beyerdynamic MMX 330 PRO

The 08.24 specification sheet lists a 'Single-sided, detachable cable with an integrated remote control'; both product pages list 'Remote: Without Remote'. · Manufacturer specification

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

No source recorded for this side.

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

Frequency equalisation

Beyerdynamic MMX 330 PRONot verified

Sennheiser HD 660S2Diffuse-field equalised

Sources

Beyerdynamic MMX 330 PRO

No source recorded for this side.

Sennheiser HD 660S2

Manufacturer specification

Sennheiser HD 660S2 — operating guide and specifications

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

Headband pressure

Beyerdynamic MMX 330 PRO5.5 N

Sennheiser HD 660S2Not verified

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification

beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

No source recorded for this side.

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

In the box

Beyerdynamic MMX 330 PROHeadset, connection cable with 2 × 3-pole 3.5 mm plugs, adapter to a 4-pole 3.5 mm combination plug

Sennheiser HD 660S2Not verified

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification

beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

No source recorded for this side.

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

Rated long-term input power

Beyerdynamic MMX 330 PRONot verified

Sennheiser HD 660S2Maximum 500 mW under EN 60-268-7

Sources

Beyerdynamic MMX 330 PRO

No source recorded for this side.

Sennheiser HD 660S2

Manufacturer specification · Rated to EN 60-268-7; the maximum input the headphones can handle, not the amplifier power they need.

Sennheiser HD 660S2 — operating guide and specifications

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

Static magnetic field at the surface

Beyerdynamic MMX 330 PRONot verified

Sennheiser HD 660S24.5 mT

Sources

Beyerdynamic MMX 330 PRO

No source recorded for this side.

Sennheiser HD 660S2

Manufacturer specification · Static magnetic field at the headphone surface.

Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications

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

Construction

Beyerdynamic MMX 330 PROMetal parts with impact- and scratch-resistant plastic; memory-foam headband cushion with fontanelle recess; handmade in Germany

Sennheiser HD 660S2Not verified

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

No source recorded for this side.

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

Microphone specifications

Beyerdynamic MMX 330 PROCardioid back-electret condenser; 20–20,000 Hz; 21.6 mV/Pa at 1 kHz; max. SPL 121 dB; 13 mm microphone head diameter; boom approx. 190 mm

Sennheiser HD 660S2Not verified

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification · AB-powered from the device's microphone input (2–9 V, 0.6 mA); unbalanced output.

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

No source recorded for this side.

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

Operating temperature

Beyerdynamic MMX 330 PRONot verified

Sennheiser HD 660S2−10 °C to +55 °C

Sources

Beyerdynamic MMX 330 PRO

No source recorded for this side.

Sennheiser HD 660S2

Manufacturer specification

Sennheiser HD 660S2 — operating guide and specifications

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

Platform compatibility

Beyerdynamic MMX 330 PROPlayStation, Xbox, Nintendo Switch and smartphones via cable; PC via separate headphone and microphone plugs

Sennheiser HD 660S2Not verified

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification · Analogue 3.5 mm connection only; no USB or wireless connection is listed.

beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

No source recorded for this side.

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

Power handling

Beyerdynamic MMX 330 PRO30 mW

Sennheiser HD 660S2Not verified

Sources

Beyerdynamic MMX 330 PRO

Manufacturer specification

beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24)

Sennheiser HD 660S2

No source recorded for this side.

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

Replaceable parts

Beyerdynamic MMX 330 PRONot verified

Sennheiser HD 660S2Detachable cable and replaceable ear pads

Sources

Beyerdynamic MMX 330 PRO

No source recorded for this side.

Sennheiser HD 660S2

Manufacturer specification · Replacement procedures are in the manual; spare-part availability varies.

Sennheiser HD 660S2 — operating guide and specifications

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

Manufacturer sub-bass claim

Beyerdynamic MMX 330 PRONot verified

Sennheiser HD 660S2Double the sound pressure at the lowest frequencies

Sources

Beyerdynamic MMX 330 PRO

No source recorded for this side.

Sennheiser HD 660S2

Manufacturer specification · Sennheiser does not give the frequency range or comparison model for this claim.

Sennheiser HD 660S2 — exact model specifications

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

Beyerdynamic MMX 330 PRO

Select a feature to check your fit.

YOUR CHOICE

Sennheiser HD 660S2

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

Beyerdynamic MMX 330 PRO

What it brings

beyerdynamic's specification sheet lists microphone data — cardioid back-electret condenser, 20–20,000 Hz, 21.6 mV/Pa and an approx. 190 mm boom — alongside the headphone specifications.
Manufacturer source
One cable serves PC (separate headphone and microphone plugs) and, with the supplied adapter, consoles and phones with a combination jack.
Manufacturer source Manufacturer source
Ear pads, headband pad and cable are offered as replacement parts, and the headband cushion has a fontanelle recess.
Manufacturer source Manufacturer source

What to check

It is open-back: beyerdynamic recommends the closed MMX 300 PRO where other players are in the room and no sound should escape; no attenuation figure is published for the MMX 330 PRO.
Manufacturer source
It is analogue only (no USB or wireless), and beyerdynamic's sources disagree on whether the cable has an integrated remote.
Manufacturer source Manufacturer source

Sennheiser HD 660S2

What it brings

Both a 4.4 mm balanced and a 6.35 mm unbalanced cable are included with a 3.5 mm adapter, and the velour ear pads are replaceable.
Manufacturer source Manufacturer source
A revised 300-ohm voice coil, more compliant surround and vented magnet system are designed for more sub-bass, and sensitivity is rated at 104 dB SPL at 1 V.
Manufacturer source Manufacturer source

What to check

At 300 ohms with a rated 104 dB SPL at 1 kHz / 1 V rms, check that your amplifier or audio source can drive the headphones properly.
Manufacturer source Manufacturer source
The open-back design leaks sound and lets outside noise in, and the supplied cables are 1.8 m long. An XLR-4 cable is sold separately.
Manufacturer source Manufacturer source

COMPARE THE DETAILS

Full specifications

How we verify

Differences only

31 of 31 specifications Sources in each row

Source-backed specifications for Beyerdynamic MMX 330 PRO and Sennheiser HD 660S2
Specification	Beyerdynamic MMX 330 PRO	Sennheiser HD 660S2

Wearing style Sources Beyerdynamic MMX 330 PRO Manufacturer specification beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — operating guide and specifications	Over-ear (circumaural), open-back wired gaming headset with boom microphone	Over-ear (circumaural), open-back dynamic headphones
Acoustic design Sources Beyerdynamic MMX 330 PRO Manufacturer specification beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — operating guide and specifications	Open-back	Open-back
Weight without cableDifferent Sources Beyerdynamic MMX 330 PRO Manufacturer specification · The product pages state 318 g without cable; the spec sheet gives 318 g without stating the basis. beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 Manufacturer specification · Approximate, without the cable. Sennheiser HD 660S2 — operating guide and specifications	318 g	260 g
Headband pressure Sources Beyerdynamic MMX 330 PRO Manufacturer specification beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 No source recorded.	5.5 N	Not provided
EarpadsDifferent Sources Beyerdynamic MMX 330 PRO Manufacturer specification · beyerdynamic says MMX 300 PRO ear pads are not compatible with the MMX 330 PRO. beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 Manufacturer specification · Replacement procedure shown in the manual. Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications	Velour, replaceable (spare part 1001656); headband pad also replaceable	Velour ear pads; replaceable
Construction Sources Beyerdynamic MMX 330 PRO Manufacturer specification beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 No source recorded.	Metal parts with impact- and scratch-resistant plastic; memory-foam headband cushion with fontanelle recess; handmade in Germany	Not provided
Replaceable parts Sources Beyerdynamic MMX 330 PRO No source recorded. Sennheiser HD 660S2 Manufacturer specification · Replacement procedures are in the manual; spare-part availability varies. Sennheiser HD 660S2 — operating guide and specifications	Not provided	Detachable cable and replaceable ear pads
Rated contact pressure Sources Beyerdynamic MMX 330 PRO No source recorded. Sennheiser HD 660S2 Manufacturer specification · Nominal clamping force; individual fit and comfort can differ. Sennheiser HD 660S2 — operating guide and specifications	Not provided	Approximately 6.0 N ±1.0 N

Wired / wireless connectionsDifferent Sources Beyerdynamic MMX 330 PRO Manufacturer specification · The cable connects to the headset with a 5-pole jack plug. beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications	Wired; detachable single-sided 2.5 m cable ending in two 3.5 mm plugs (headphone and microphone), plus a supplied adapter to a single 3.5 mm combination jack	Wired analogue stereo; 1.8 m cables with 6.35 mm unbalanced and 4.4 mm balanced plugs; included 3.5 mm adapter
Supplied plugs and adapterDifferent Sources Beyerdynamic MMX 330 PRO Manufacturer specification beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 Manufacturer specification · The 4.4 mm balanced cable needs a balanced headphone output; an XLR-4 cable is optional. Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications	2 × 3-pole 3.5 mm plugs (headphone / microphone); adapter from 2 × 3.5 mm sockets to 1 × 4-pole 3.5 mm plug	6.35 mm unbalanced cable; 4.4 mm balanced cable; 6.35 mm-to-3.5 mm adapter
Cable arrangementDifferent Sources Beyerdynamic MMX 330 PRO Manufacturer specification beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 Manufacturer specification · Optional cables are sold separately; balanced cables need a balanced headphone output. Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications	Detachable, single-sided straight cable	Detachable 1.8 m unbalanced and 4.4 mm balanced cables included; XLR-4 cable optional
Cable lengthDifferent Sources Beyerdynamic MMX 330 PRO Manufacturer specification beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 Manufacturer specification · Length of the supplied cable. Sennheiser HD 660S2 — operating guide and specifications	2.5 m	1.8 m
Battery life Sources Beyerdynamic MMX 330 PRO Manufacturer specification · Passive headphones with no battery or charging; the condenser microphone takes its supply from the connected device's microphone input. beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 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 660S2 — operating guide and specifications	Not required: passive wired headset powered by the audio source	Not listed by the manufacturer
Platform compatibility Sources Beyerdynamic MMX 330 PRO Manufacturer specification · Analogue 3.5 mm connection only; no USB or wireless connection is listed. beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 No source recorded.	PlayStation, Xbox, Nintendo Switch and smartphones via cable; PC via separate headphone and microphone plugs	Not provided

Driver constructionDifferent Sources Beyerdynamic MMX 330 PRO Manufacturer specification · beyerdynamic's driver name; a diameter is not stated in the sources read. beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 Manufacturer specification · Sennheiser lists 38 mm as the transducer size. Sennheiser HD 660S2 — exact model specifications	Dynamic STELLAR.45 driver	38 mm open dynamic transducer; aluminium voice coil and vented magnet system
Nominal impedanceDifferent Sources Beyerdynamic MMX 330 PRO Manufacturer specification beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 Manufacturer specification · Nominal impedance; check that your amplifier or audio source can drive this load. Sennheiser HD 660S2 — operating guide and specifications	48 ohm	300 ohm
Rated frequency rangeDifferent Sources Beyerdynamic MMX 330 PRO Manufacturer specification beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — operating guide and specifications	5–40,000 Hz	8–41,500 Hz (−10 dB)
Rated sensitivityDifferent Sources Beyerdynamic MMX 330 PRO Manufacturer specification beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 Manufacturer specification · Rated at 1 kHz with 1 V rms; not directly comparable with dB/mW ratings. Sennheiser HD 660S2 — operating guide and specifications	96 dB SPL at 1 mW / 500 Hz	104 dB SPL at 1 kHz, 1 V rms
Rated total harmonic distortionDifferent Sources Beyerdynamic MMX 330 PRO Manufacturer specification beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 Manufacturer specification · Rated at 1 kHz and 100 dB SPL; other models use different test levels, so compare with care. Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications	<0.05% at 500 Hz	≤0.04% at 1 kHz, 100 dB SPL
Power handling Sources Beyerdynamic MMX 330 PRO Manufacturer specification beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 No source recorded.	30 mW	Not provided
Frequency equalisation Sources Beyerdynamic MMX 330 PRO No source recorded. Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — operating guide and specifications	Not provided	Diffuse-field equalised
Rated long-term input power Sources Beyerdynamic MMX 330 PRO No source recorded. Sennheiser HD 660S2 Manufacturer specification · Rated to EN 60-268-7; the maximum input the headphones can handle, not the amplifier power they need. Sennheiser HD 660S2 — operating guide and specifications	Not provided	Maximum 500 mW under EN 60-268-7
Published acoustic changes Sources Beyerdynamic MMX 330 PRO No source recorded. Sennheiser HD 660S2 Manufacturer specification · Sennheiser describes these changes as the S2 revision of the HD 660S. Sennheiser HD 660S2 — exact model specifications	Not provided	Revised 300-ohm coil, more compliant surround, 70 Hz resonance and revised transducer airflow
Manufacturer sub-bass claim Sources Beyerdynamic MMX 330 PRO No source recorded. Sennheiser HD 660S2 Manufacturer specification · Sennheiser does not give the frequency range or comparison model for this claim. Sennheiser HD 660S2 — exact model specifications	Not provided	Double the sound pressure at the lowest frequencies

Microphone Sources Beyerdynamic MMX 330 PRO Manufacturer specification · Cardioid back-electret condenser boom microphone; boom approx. 190 mm. beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 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 660S2 — operating guide and specifications	Yes	Not listed by the manufacturer
Microphone specifications Sources Beyerdynamic MMX 330 PRO Manufacturer specification · AB-powered from the device's microphone input (2–9 V, 0.6 mA); unbalanced output. beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 No source recorded.	Cardioid back-electret condenser; 20–20,000 Hz; 21.6 mV/Pa at 1 kHz; max. SPL 121 dB; 13 mm microphone head diameter; boom approx. 190 mm	Not provided
Active noise cancellation Sources Beyerdynamic MMX 330 PRO Manufacturer specification · Passive, open-back wired headset; no active noise cancellation is listed. beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 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 660S2 — operating guide and specifications	No	Not listed by the manufacturer

In the box Sources Beyerdynamic MMX 330 PRO Manufacturer specification beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 No source recorded.	Headset, connection cable with 2 × 3-pole 3.5 mm plugs, adapter to a 4-pole 3.5 mm combination plug	Not provided

Static magnetic field at the surface Sources Beyerdynamic MMX 330 PRO No source recorded. Sennheiser HD 660S2 Manufacturer specification · Static magnetic field at the headphone surface. Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications	Not provided	4.5 mT
Operating temperature Sources Beyerdynamic MMX 330 PRO No source recorded. Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — operating guide and specifications	Not provided	−10 °C to +55 °C

Show unverified (1)Not verified, not provided or conflicting for both products. Kept for completeness; never counted as a difference.

Specifications without verified values for either product
Cable remote Sources Beyerdynamic MMX 330 PRO The 08.24 specification sheet lists a 'Single-sided, detachable cable with an integrated remote control'; both product pages list 'Remote: Without Remote'. · Manufacturer specification beyerdynamic MMX 330 PRO — global product page and technical data beyerdynamic MMX 330 PRO — English specification sheet (E1, 08.24) Sennheiser HD 660S2 No source recorded.	Conflicting sources	Not provided

First product manufacturer source Second product manufacturer source

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