HEADPHONES · YOUR NEXT FACE-OFF

Beats Powerbeats Fit vs Sennheiser HD 660S2

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

Compared products

YOUR FIRST CHOICE

Beats Powerbeats Fit

ME2J4ZM/A · Jet Black · UK

Full product profile Official image

Exact model & source notes

Powerbeats Fit (ME2J4ZM/A in Jet Black in the UK, ME2J4LL/A in the US) are Beats' wing-tip workout earbuds with active noise cancelling, Transparency mode and Apple's H1 chip, and they work with Apple and Android devices (the Beats app for Android adds extra features). Beats rates them at up to 7 hours per charge with ANC off (6 hours with ANC on) and 30 hours with the case.

Specifications checked 26 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 Beats Powerbeats Fit for

A wireless connection

Choose the Sennheiser HD 660S2 for

A wired connection

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

See the 3 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

Beats Powerbeats Fit 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 SIDE6 topics

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

SELECTED TOPIC

01 / 06

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.

Beats Powerbeats FitNot verified

Sennheiser HD 660S2Yes

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 ↓

3 verified differences, most decision-relevant first. Missing information stays separate.

Wired / wireless connections

Beats Powerbeats FitClass 1 Bluetooth (version not stated); USB-C case charging

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

Beats Powerbeats Fit

Manufacturer specification · Beats does not state a Bluetooth version on the UK or US page. Power adapter and USB-C cable sold separately; no wireless charging is listed.

Beats (UK) — Powerbeats Fit product page, tech specs and FAQ

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.

Driver construction

Beats Powerbeats FitAxial-aligned drivers

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

Sources

Beats Powerbeats Fit

Manufacturer specification · Beats says the earbud’s ergonomic shape is built around axial-aligned drivers; it does not state a driver size.

Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Beats (US) — Powerbeats Fit product page, tech specs and FAQ

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.

Wearing style

Beats Powerbeats FitIn-ear, true wireless with flexible wing tips

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

Sources

Beats Powerbeats Fit

Manufacturer specification · Two separate earbuds with a one-size flexible wing tip and ear tips in four sizes (XS, S, M, L), supplied with a charging case.

Beats (UK) — Powerbeats Fit product page, tech specs and FAQ

Sennheiser HD 660S2

Manufacturer specification

Sennheiser HD 660S2 — operating guide and specifications

Check the exact configuration and source conditions for your use.

Missing or non-comparable evidence (29)

Acoustic design

Beats Powerbeats FitNot verified

Sennheiser HD 660S2Open-back

Sources

Beats Powerbeats Fit

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.

Active noise cancellation

Beats Powerbeats FitYes

Sennheiser HD 660S2Not verified

Sources

Beats Powerbeats Fit

Manufacturer specification · Active Noise Cancelling and Transparency mode.

Beats (UK) — Powerbeats Fit product page, tech specs and FAQ

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

Beats Powerbeats FitYes

Sennheiser HD 660S2Not verified

Sources

Beats Powerbeats Fit

Manufacturer specification · Three microphones per earbud (six in total) with beam-forming for calls; an internal processor reduces external noise such as wind.

Beats (UK) — Powerbeats Fit product page, tech specs and FAQ

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

Beats Powerbeats FitEarbuds: up to 7 hours with ANC or Transparency off, up to 6 hours with ANC or Transparency on. With the charging case (around three additional charges): up to 30 hours with ANC/Transparency off, 24 hours with ANC/Transparency on. Fast Fuel: 5 minutes gives up to 1 hour.

Sennheiser HD 660S2Not verified

Sources

Beats Powerbeats Fit

Manufacturer specification · Apple's tests (May 2025, pre-production units paired with iPhone 15 Pro, 50% volume) ran until the first earbud stopped playback. The Fast Fuel figure was measured with ANC and Transparency off via a USB-C cable.

Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Beats (US) — Powerbeats Fit product page, tech specs and FAQ Beats (UK) — Compare products (feature data and battery footnotes)

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.

Nominal impedance

Beats Powerbeats FitNot verified

Sennheiser HD 660S2300 ohm

Sources

Beats Powerbeats Fit

No source recorded for this side.

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

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

Published acoustic changes

Beats Powerbeats FitNot verified

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

Sources

Beats Powerbeats Fit

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.

Adaptive EQ

Beats Powerbeats FitYes

Sennheiser HD 660S2Not verified

Sources

Beats Powerbeats Fit

Manufacturer specification · With ANC and Transparency off, Adaptive EQ uses up to five microphones to tailor sound to the fit and seal of each earbud.

Beats (UK) — Powerbeats Fit product page, tech specs and FAQ

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.

Companion app

Beats Powerbeats FitBeats app for Android: one-touch pairing, customisable controls, battery status, Locate My Beats and a Fit Test

Sennheiser HD 660S2Not verified

Sources

Beats Powerbeats Fit

Manufacturer specification · Beats lists the app under Android compatibility; on Android the Beats app is also used to check and update firmware.

Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Beats (US) — Powerbeats Fit product page, tech specs and FAQ

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.

Included and optional cables

Beats Powerbeats FitNot verified

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

Sources

Beats Powerbeats Fit

No source recorded for this side.

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

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

Included cable length

Beats Powerbeats FitNot verified

Sennheiser HD 660S21.8 m

Sources

Beats Powerbeats Fit

No source recorded for this side.

Sennheiser HD 660S2

Manufacturer specification · Length of the supplied cable.

Sennheiser HD 660S2 — operating guide and specifications

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

Headphone chip

Beats Powerbeats FitApple H1

Sennheiser HD 660S2Not verified

Sources

Beats Powerbeats Fit

Manufacturer specification · With iOS devices: one-touch pairing, automatic switching, Audio Sharing, hands-free Hey Siri, Find My and Fit Test.

Beats (UK) — Powerbeats Fit product page, tech specs and FAQ

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.

Supplied plug configuration

Beats Powerbeats FitNot verified

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

Sources

Beats Powerbeats Fit

No source recorded for this side.

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

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

Rated contact pressure

Beats Powerbeats FitNot verified

Sennheiser HD 660S2Approximately 6.0 N ±1.0 N

Sources

Beats Powerbeats Fit

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.

Earbud controls

Beats Powerbeats FitSingle multi-function 'b' button per earbud (customisable, including volume); auto play/pause

Sennheiser HD 660S2Not verified

Sources

Beats Powerbeats Fit

Manufacturer specification · Default presses: once to play or pause, twice to skip forwards, three times to skip backwards. The buttons can be set to manage music, adjust volume, toggle listening modes, take calls and activate the voice assistant.

Beats (UK) — Powerbeats Fit product page, tech specs and FAQ

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 total harmonic distortion

Beats Powerbeats FitNot verified

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

Sources

Beats Powerbeats Fit

No source recorded for this side.

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

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

Ear pads

Beats Powerbeats FitNot verified

Sennheiser HD 660S2Velour ear pads; replaceable

Sources

Beats Powerbeats Fit

No source recorded for this side.

Sennheiser HD 660S2

Manufacturer specification · Replacement procedure shown in the manual.

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.

Frequency equalisation

Beats Powerbeats FitNot verified

Sennheiser HD 660S2Diffuse-field equalised

Sources

Beats Powerbeats Fit

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.

Rated frequency range

Beats Powerbeats FitNot verified

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

Sources

Beats Powerbeats Fit

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.

Rated long-term input power

Beats Powerbeats FitNot verified

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

Sources

Beats Powerbeats Fit

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

Beats Powerbeats FitNot verified

Sennheiser HD 660S24.5 mT

Sources

Beats Powerbeats Fit

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.

Operating temperature

Beats Powerbeats FitNot verified

Sennheiser HD 660S2−10 °C to +55 °C

Sources

Beats Powerbeats Fit

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.

Rated sensitivity

Beats Powerbeats FitNot verified

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

Sources

Beats Powerbeats Fit

No source recorded for this side.

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

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

Replaceable parts

Beats Powerbeats FitNot verified

Sennheiser HD 660S2Detachable cable and replaceable ear pads

Sources

Beats Powerbeats Fit

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.

Spatial audio

Beats Powerbeats FitPersonalised spatial audio with dynamic head tracking

Sennheiser HD 660S2Not verified

Sources

Beats Powerbeats Fit

Manufacturer specification

Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Beats (US) — Powerbeats Fit product page, tech specs and FAQ

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.

Manufacturer sub-bass claim

Beats Powerbeats FitNot verified

Sennheiser HD 660S2Double the sound pressure at the lowest frequencies

Sources

Beats Powerbeats Fit

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.

Dust, sweat and water resistance

Beats Powerbeats FitIPX4 (earbuds and charging case)

Sennheiser HD 660S2Not verified

Sources

Beats Powerbeats Fit

Manufacturer specification

Beats (UK) — Powerbeats Fit product page, tech specs and FAQ

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.

Weight per earbud

Beats Powerbeats Fit5.78 g

Sennheiser HD 660S2Not verified

Sources

Beats Powerbeats Fit

Manufacturer specification · Each earbud. The charging case weighs 49.75 g; Beats gives 61.3 g in total.

Beats (UK) — Powerbeats Fit product page, tech specs and FAQ

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.

Dimensions

Beats Powerbeats FitEarbud: 2.74 cm long, 2.15 cm wide, 2.04 cm high; charging case: 6.25 cm long, 5.54 cm wide, 2.75 cm high

Sennheiser HD 660S2Not verified

Sources

Beats Powerbeats Fit

Manufacturer specification

Beats (UK) — Powerbeats Fit product page, tech specs and FAQ

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.

Weight

Beats Powerbeats FitNot verified

Sennheiser HD 660S2260 g

Sources

Beats Powerbeats Fit

No source recorded for this side.

Sennheiser HD 660S2

Manufacturer specification · Approximate, without the cable.

Sennheiser HD 660S2 — operating guide and specifications

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

0 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

Beats Powerbeats Fit

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

Beats Powerbeats Fit

What it brings

A flexible one-size wing tip tucks under the ridge of the upper ear to hold each earbud in place, and at 5.78 g per bud and 49.75 g for the case they are lighter than Powerbeats Pro 2 (8.7 g and 69.0 g).
Manufacturer source Manufacturer source
Both the earbuds and the charging case are rated IPX4 for sweat and water, and the page lists ANC, Transparency, Adaptive EQ and personalised spatial audio.
Manufacturer source

What to check

Shorter rated battery than Powerbeats Pro 2: 6 hours per charge with ANC on and 24 hours with the case, versus 8 and 36 hours, and no wireless charging is listed for the case.
Manufacturer source Manufacturer source
Uses the Apple H1 chip where Powerbeats Pro 2 uses H2, has a single multi-function button per earbud with no volume rockers listed (the buttons can be set to adjust volume), and ships without a charging cable. Beats gives no Bluetooth version.
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

32 of 32 specifications Sources in each row

Source-backed specifications for Beats Powerbeats Fit and Sennheiser HD 660S2
Specification	Beats Powerbeats Fit	Sennheiser HD 660S2

Wearing styleDifferent Sources Beats Powerbeats Fit Manufacturer specification · Two separate earbuds with a one-size flexible wing tip and ear tips in four sizes (XS, S, M, L), supplied with a charging case. Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — operating guide and specifications	In-ear, true wireless with flexible wing tips	Over-ear (circumaural), open-back dynamic headphones
Weight per earbud Sources Beats Powerbeats Fit Manufacturer specification · Each earbud. The charging case weighs 49.75 g; Beats gives 61.3 g in total. Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Sennheiser HD 660S2 No source recorded.	5.78 g	Not provided
Dimensions Sources Beats Powerbeats Fit Manufacturer specification Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Sennheiser HD 660S2 No source recorded.	Earbud: 2.74 cm long, 2.15 cm wide, 2.04 cm high; charging case: 6.25 cm long, 5.54 cm wide, 2.75 cm high	Not provided
Dust, sweat and water resistance Sources Beats Powerbeats Fit Manufacturer specification Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Sennheiser HD 660S2 No source recorded.	IPX4 (earbuds and charging case)	Not provided
Weight Sources Beats Powerbeats Fit No source recorded. Sennheiser HD 660S2 Manufacturer specification · Approximate, without the cable. Sennheiser HD 660S2 — operating guide and specifications	Not provided	260 g
Acoustic design Sources Beats Powerbeats Fit No source recorded. Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — operating guide and specifications	Not provided	Open-back
Replaceable parts Sources Beats Powerbeats Fit 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
Ear pads Sources Beats Powerbeats Fit No source recorded. Sennheiser HD 660S2 Manufacturer specification · Replacement procedure shown in the manual. Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications	Not provided	Velour ear pads; replaceable
Rated contact pressure Sources Beats Powerbeats Fit 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 Beats Powerbeats Fit Manufacturer specification · Beats does not state a Bluetooth version on the UK or US page. Power adapter and USB-C cable sold separately; no wireless charging is listed. Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications	Class 1 Bluetooth (version not stated); USB-C case charging	Wired analogue stereo; 1.8 m cables with 6.35 mm unbalanced and 4.4 mm balanced plugs; included 3.5 mm adapter
Battery life Sources Beats Powerbeats Fit Manufacturer specification · Apple's tests (May 2025, pre-production units paired with iPhone 15 Pro, 50% volume) ran until the first earbud stopped playback. The Fast Fuel figure was measured with ANC and Transparency off via a USB-C cable. Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Beats (US) — Powerbeats Fit product page, tech specs and FAQ Beats (UK) — Compare products (feature data and battery footnotes) 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	Earbuds: up to 7 hours with ANC or Transparency off, up to 6 hours with ANC or Transparency on. With the charging case (around three additional charges): up to 30 hours with ANC/Transparency off, 24 hours with ANC/Transparency on. Fast Fuel: 5 minutes gives up to 1 hour.	Not listed by the manufacturer
Included cable length Sources Beats Powerbeats Fit No source recorded. Sennheiser HD 660S2 Manufacturer specification · Length of the supplied cable. Sennheiser HD 660S2 — operating guide and specifications	Not provided	1.8 m
Supplied plug configuration Sources Beats Powerbeats Fit No source recorded. 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	Not provided	6.35 mm unbalanced cable; 4.4 mm balanced cable; 6.35 mm-to-3.5 mm adapter
Included and optional cables Sources Beats Powerbeats Fit No source recorded. 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	Not provided	Detachable 1.8 m unbalanced and 4.4 mm balanced cables included; XLR-4 cable optional

Driver constructionDifferent Sources Beats Powerbeats Fit Manufacturer specification · Beats says the earbud’s ergonomic shape is built around axial-aligned drivers; it does not state a driver size. Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Beats (US) — Powerbeats Fit product page, tech specs and FAQ Sennheiser HD 660S2 Manufacturer specification · Sennheiser lists 38 mm as the transducer size. Sennheiser HD 660S2 — exact model specifications	Axial-aligned drivers	38 mm open dynamic transducer; aluminium voice coil and vented magnet system
Spatial audio Sources Beats Powerbeats Fit Manufacturer specification Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Beats (US) — Powerbeats Fit product page, tech specs and FAQ Sennheiser HD 660S2 No source recorded.	Personalised spatial audio with dynamic head tracking	Not provided
Adaptive EQ Sources Beats Powerbeats Fit Manufacturer specification · With ANC and Transparency off, Adaptive EQ uses up to five microphones to tailor sound to the fit and seal of each earbud. Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Sennheiser HD 660S2 No source recorded.	Yes	Not provided
Headphone chip Sources Beats Powerbeats Fit Manufacturer specification · With iOS devices: one-touch pairing, automatic switching, Audio Sharing, hands-free Hey Siri, Find My and Fit Test. Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Sennheiser HD 660S2 No source recorded.	Apple H1	Not provided
Nominal impedance Sources Beats Powerbeats Fit No source recorded. 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	Not provided	300 ohm
Rated frequency range Sources Beats Powerbeats Fit No source recorded. Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — operating guide and specifications	Not provided	8–41,500 Hz (−10 dB)
Rated sensitivity Sources Beats Powerbeats Fit No source recorded. 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	Not provided	104 dB SPL at 1 kHz, 1 V rms
Frequency equalisation Sources Beats Powerbeats Fit No source recorded. Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — operating guide and specifications	Not provided	Diffuse-field equalised
Rated total harmonic distortion Sources Beats Powerbeats Fit No source recorded. 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	Not provided	≤0.04% at 1 kHz, 100 dB SPL
Rated long-term input power Sources Beats Powerbeats Fit 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 Beats Powerbeats Fit 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 Beats Powerbeats Fit 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 Beats Powerbeats Fit Manufacturer specification · Three microphones per earbud (six in total) with beam-forming for calls; an internal processor reduces external noise such as wind. Beats (UK) — Powerbeats Fit product page, tech specs and FAQ 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
Active noise cancellation Sources Beats Powerbeats Fit Manufacturer specification · Active Noise Cancelling and Transparency mode. Beats (UK) — Powerbeats Fit product page, tech specs and FAQ 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	Yes	Not listed by the manufacturer

Companion app Sources Beats Powerbeats Fit Manufacturer specification · Beats lists the app under Android compatibility; on Android the Beats app is also used to check and update firmware. Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Beats (US) — Powerbeats Fit product page, tech specs and FAQ Sennheiser HD 660S2 No source recorded.	Beats app for Android: one-touch pairing, customisable controls, battery status, Locate My Beats and a Fit Test	Not provided
Earbud controls Sources Beats Powerbeats Fit Manufacturer specification · Default presses: once to play or pause, twice to skip forwards, three times to skip backwards. The buttons can be set to manage music, adjust volume, toggle listening modes, take calls and activate the voice assistant. Beats (UK) — Powerbeats Fit product page, tech specs and FAQ Sennheiser HD 660S2 No source recorded.	Single multi-function 'b' button per earbud (customisable, including volume); auto play/pause	Not provided

Static magnetic field at the surface Sources Beats Powerbeats Fit 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 Beats Powerbeats Fit No source recorded. Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — operating guide and specifications	Not provided	−10 °C to +55 °C

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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.