HEADPHONES · YOUR NEXT FACE-OFF

Beats Solo Buds vs Sennheiser HD 660S2

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

Compared products

YOUR FIRST CHOICE

Beats Solo Buds

MUVW3ZM/A · Matt Black · UK

Full product profile Official image

Exact model & source notes

Beats Solo Buds (MUVW3ZM/A in Matt Black in the UK, MUVW3LL/A in the US) are Beats' true wireless earbuds without noise cancelling, with Bluetooth 5.3, iOS and Android compatibility (one-touch pairing, automatic pre-pairing, Find My or Find My Device) and up to 18 hours of rated battery in the earbuds themselves. The case provides no standalone charging: the earbuds recharge while seated in it with the case connected to USB-C power.

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 Solo Buds 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 Solo Buds 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 Solo BudsNot 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 Solo BudsBluetooth 5.3 (Class 1); USB-C charging through the carrying case

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 Solo Buds

Manufacturer specification · The earbuds charge only while seated in the case and the case is connected to a USB-C power source; Beats says the earbuds can be charged this way directly from a phone (requires iPhone 15 or supported Android devices), tablet or laptop. No cable or power adapter is included.

Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Beats (US) — Beats Solo Buds 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.

Drivers

Beats Solo BudsCustom dual-layer drivers, axial-aligned (positioned parallel to the acoustic nozzle)

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

Sources

Beats Solo Buds

Manufacturer specification

Beats (UK) — Beats Solo Buds product page, tech specs and footnotes

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 Solo BudsIn-ear, true wireless

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

Sources

Beats Solo Buds

Manufacturer specification · Two separate earbuds with ear tips in four sizes (XS, S, M, L), supplied with a carrying case that Beats says is designed for storage and protection but does not charge the earbuds. Beats lists ergonomically angled acoustic nozzles and laser-cut vents to improve bass and relieve air pressure.

Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Beats (US) — Beats Solo Buds 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 (25)

Acoustic design

Beats Solo BudsNot verified

Sennheiser HD 660S2Open-back

Sources

Beats Solo Buds

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 Solo BudsNo

Sennheiser HD 660S2Not verified

Sources

Beats Solo Buds

Manufacturer specification · Beats states the earbuds do not feature noise cancellation and lists no Transparency mode; the four ear-tip sizes help ensure comfort and passive noise isolation.

Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Beats (US) — Beats Solo Buds 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 Solo BudsYes

Sennheiser HD 660S2Not verified

Sources

Beats Solo Buds

Manufacturer specification · One microphone per earbud with a noise-learning algorithm for calls.

Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Beats (US) — Beats Solo Buds 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 Solo BudsEarbuds: up to 18 hours of playback per charge; no ANC. The case provides no standalone charging or additional playback total. Recharge the seated earbuds with the case connected to USB-C power. Fast Fuel: 5 minutes of charging gives up to 1 hour of playback.

Sennheiser HD 660S2Not verified

Sources

Beats Solo Buds

Manufacturer specification · Apple tested preproduction Beats Solo Buds and software in April 2024 with iPhone 15 Pro and prerelease software, 358 iTunes tracks encoded as 256-Kbps AAC and 50% volume. Full-discharge playback ended when the first earbud stopped. Battery life varies with settings, environment and use. Fast Fuel is a separate manufacturer charging claim. Charging requires the earbuds seated in the case with the case connected to a USB-C power source.

Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Beats (US) — Beats Solo Buds product page, tech specs and FAQ

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 Solo BudsNot verified

Sennheiser HD 660S2300 ohm

Sources

Beats Solo Buds

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 Solo BudsNot verified

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

Sources

Beats Solo Buds

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.

Included and optional cables

Beats Solo BudsNot verified

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

Sources

Beats Solo Buds

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 Solo BudsNot verified

Sennheiser HD 660S21.8 m

Sources

Beats Solo Buds

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.

Supplied plug configuration

Beats Solo BudsNot verified

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

Sources

Beats Solo Buds

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 Solo BudsNot verified

Sennheiser HD 660S2Approximately 6.0 N ±1.0 N

Sources

Beats Solo Buds

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 Solo BudsSingle multifunction 'b' button per earbud (customisable; can be set to control volume)

Sennheiser HD 660S2Not verified

Sources

Beats Solo Buds

Manufacturer specification · Controls music, calls and voice assistant; the 'b' button can be configured in iOS settings or the Beats app to control volume (up on one side, down on the other).

Beats (UK) — Beats Solo Buds product page, tech specs and footnotes

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 Solo BudsNot verified

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

Sources

Beats Solo Buds

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 Solo BudsNot verified

Sennheiser HD 660S2Velour ear pads; replaceable

Sources

Beats Solo Buds

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 Solo BudsNot verified

Sennheiser HD 660S2Diffuse-field equalised

Sources

Beats Solo Buds

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 Solo BudsNot verified

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

Sources

Beats Solo Buds

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 Solo BudsNot verified

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

Sources

Beats Solo Buds

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 Solo BudsNot verified

Sennheiser HD 660S24.5 mT

Sources

Beats Solo Buds

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 Solo BudsNot verified

Sennheiser HD 660S2−10 °C to +55 °C

Sources

Beats Solo Buds

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.

iOS and Android features

Beats Solo BudsCompatible with iOS and Android out of the box: one-touch pairing, automatic pre-pairing across your devices, plus Find My or Find My Device

Sennheiser HD 660S2Not verified

Sources

Beats Solo Buds

Manufacturer specification · Beats: requires an iCloud account and a compatible Apple device running the latest operating system software, or a compatible Android device running the latest operating system software with Google Play Services enabled.

Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Beats (US) — Beats Solo Buds 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 sensitivity

Beats Solo BudsNot verified

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

Sources

Beats Solo Buds

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 Solo BudsNot verified

Sennheiser HD 660S2Detachable cable and replaceable ear pads

Sources

Beats Solo Buds

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

Beats Solo BudsNot verified

Sennheiser HD 660S2Double the sound pressure at the lowest frequencies

Sources

Beats Solo Buds

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.

Weight per earbud

Beats Solo Buds5.7 g

Sennheiser HD 660S2Not verified

Sources

Beats Solo Buds

Manufacturer specification · Each earbud. The carrying case weighs 22 g.

Beats (UK) — Beats Solo Buds product page, tech specs and footnotes

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 Solo BudsEarbud: 2.05 cm long, 1.85 cm wide, 1.9 cm high; carrying case: 6.6 cm long, 3.5 cm wide, 2.4 cm high

Sennheiser HD 660S2Not verified

Sources

Beats Solo Buds

Manufacturer specification

Beats (UK) — Beats Solo Buds product page, tech specs and footnotes

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 Solo BudsNot verified

Sennheiser HD 660S2260 g

Sources

Beats Solo Buds

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 Solo Buds

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 Solo Buds

What it brings

Up to 18 hours of rated playback per charge from the earbuds alone, under Apple’s disclosed iPhone 15 Pro and 50% volume test conditions.
Manufacturer source
Beats calls the carrying case the smallest, lightest it has ever made: it weighs 22 g, each earbud weighs 5.7 g, and the earbuds can be charged in the case directly from a compatible phone, tablet or laptop over USB-C.
Manufacturer source

What to check

Beats explicitly states no active noise cancellation. Four ear-tip sizes provide fit options and passive isolation; Transparency mode support is unspecified.
Manufacturer source Manufacturer source
The case cannot recharge the earbuds on its own. Charging requires the earbuds seated in the case with the case connected to a USB-C power source; no cable is included.
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

28 of 28 specifications Sources in each row

Source-backed specifications for Beats Solo Buds and Sennheiser HD 660S2
Specification	Beats Solo Buds	Sennheiser HD 660S2

Wearing styleDifferent Sources Beats Solo Buds Manufacturer specification · Two separate earbuds with ear tips in four sizes (XS, S, M, L), supplied with a carrying case that Beats says is designed for storage and protection but does not charge the earbuds. Beats lists ergonomically angled acoustic nozzles and laser-cut vents to improve bass and relieve air pressure. Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Beats (US) — Beats Solo Buds product page, tech specs and FAQ Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — operating guide and specifications	In-ear, true wireless	Over-ear (circumaural), open-back dynamic headphones
Weight per earbud Sources Beats Solo Buds Manufacturer specification · Each earbud. The carrying case weighs 22 g. Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Sennheiser HD 660S2 No source recorded.	5.7 g	Not provided
Dimensions Sources Beats Solo Buds Manufacturer specification Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Sennheiser HD 660S2 No source recorded.	Earbud: 2.05 cm long, 1.85 cm wide, 1.9 cm high; carrying case: 6.6 cm long, 3.5 cm wide, 2.4 cm high	Not provided
Weight Sources Beats Solo Buds 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 Solo Buds No source recorded. Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — operating guide and specifications	Not provided	Open-back
Replaceable parts Sources Beats Solo Buds 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 Solo Buds 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 Solo Buds 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 Solo Buds Manufacturer specification · The earbuds charge only while seated in the case and the case is connected to a USB-C power source; Beats says the earbuds can be charged this way directly from a phone (requires iPhone 15 or supported Android devices), tablet or laptop. No cable or power adapter is included. Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Beats (US) — Beats Solo Buds product page, tech specs and FAQ Sennheiser HD 660S2 Manufacturer specification Sennheiser HD 660S2 — exact model specifications Sennheiser HD 660S2 — operating guide and specifications	Bluetooth 5.3 (Class 1); USB-C charging through the carrying case	Wired analogue stereo; 1.8 m cables with 6.35 mm unbalanced and 4.4 mm balanced plugs; included 3.5 mm adapter
iOS and Android features Sources Beats Solo Buds Manufacturer specification · Beats: requires an iCloud account and a compatible Apple device running the latest operating system software, or a compatible Android device running the latest operating system software with Google Play Services enabled. Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Beats (US) — Beats Solo Buds product page, tech specs and FAQ Sennheiser HD 660S2 No source recorded.	Compatible with iOS and Android out of the box: one-touch pairing, automatic pre-pairing across your devices, plus Find My or Find My Device	Not provided
Battery life Sources Beats Solo Buds Manufacturer specification · Apple tested preproduction Beats Solo Buds and software in April 2024 with iPhone 15 Pro and prerelease software, 358 iTunes tracks encoded as 256-Kbps AAC and 50% volume. Full-discharge playback ended when the first earbud stopped. Battery life varies with settings, environment and use. Fast Fuel is a separate manufacturer charging claim. Charging requires the earbuds seated in the case with the case connected to a USB-C power source. Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Beats (US) — Beats Solo Buds product page, tech specs and FAQ 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 18 hours of playback per charge; no ANC. The case provides no standalone charging or additional playback total. Recharge the seated earbuds with the case connected to USB-C power. Fast Fuel: 5 minutes of charging gives up to 1 hour of playback.	Not listed by the manufacturer
Included cable length Sources Beats Solo Buds 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 Solo Buds 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 Solo Buds 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

DriversDifferent Sources Beats Solo Buds Manufacturer specification Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Sennheiser HD 660S2 Manufacturer specification · Sennheiser lists 38 mm as the transducer size. Sennheiser HD 660S2 — exact model specifications	Custom dual-layer drivers, axial-aligned (positioned parallel to the acoustic nozzle)	38 mm open dynamic transducer; aluminium voice coil and vented magnet system
Nominal impedance Sources Beats Solo Buds 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 Solo Buds 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 Solo Buds 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 Solo Buds 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 Solo Buds 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 Solo Buds 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 Solo Buds 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 Solo Buds 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 Solo Buds Manufacturer specification · One microphone per earbud with a noise-learning algorithm for calls. Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Beats (US) — Beats Solo Buds 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 Solo Buds Manufacturer specification · Beats states the earbuds do not feature noise cancellation and lists no Transparency mode; the four ear-tip sizes help ensure comfort and passive noise isolation. Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Beats (US) — Beats Solo Buds 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	No	Not listed by the manufacturer

Earbud controls Sources Beats Solo Buds Manufacturer specification · Controls music, calls and voice assistant; the 'b' button can be configured in iOS settings or the Beats app to control volume (up on one side, down on the other). Beats (UK) — Beats Solo Buds product page, tech specs and footnotes Sennheiser HD 660S2 No source recorded.	Single multifunction 'b' button per earbud (customisable; can be set to control volume)	Not provided

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

First product manufacturer source Second product manufacturer source

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