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HEADPHONES · YOUR NEXT FACE-OFF

Nothing CMF Buds 2a vs Sennheiser HD 800 S

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

Compared products

YOUR FIRST CHOICE

Nothing CMF Buds 2a

6974434225138 · Orange · UK

CMF Buds 2a orange earbuds in an open orange charging case marked Buds 2A
Exact model & source notes

CMF Buds 2a (store SKU 6974434225138 in Orange on the UK and US Nothing stores) are true wireless earbuds with ANC up to 42 dB, a 12.4 mm bio-fibre driver, four microphones and Bluetooth 5.4 with dual connection.

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 Nothing CMF Buds 2a for

  • A wireless connection

Choose the Sennheiser HD 800 S 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 800 S

Black · HD 800 S · 506911

Black Sennheiser HD 800 S open-back headphones with ring-radiator earcups and detachable cable connectors visible
Exact model & source notes

The HD 800 S is an open-back, over-ear headphone built around a 56 mm ring-radiator driver with an acoustic absorber. It is rated 4–51,000 Hz (−10 dB) at 300 ohms and ships with detachable 3 m cables in both 6.35 mm unbalanced and 4.4 mm balanced form.

Specifications checked 11 Sept 2026.

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

Manufacturer specifications

Nothing CMF Buds 2a UK & US retailers

UK & US price history: no verified listing yet

Sennheiser HD 800 S 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.

Nothing CMF Buds 2aNot verified
Sennheiser HD 800 SYes

Open-back. Manufacturer specification

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

Nothing CMF Buds 2aBluetooth 5.4 (AAC, SBC) with dual connection; USB-C charging on the case
Sennheiser HD 800 SWired analogue; detachable 6.35 mm unbalanced and 4.4 mm balanced cables
Sources
Nothing CMF Buds 2a

Manufacturer specification · The manufacturer lists AAC and SBC codec support; support for other codecs remains unverified. Charging is quoted with a Type-C cable.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

Manufacturer specification · The XLR-4 cable is an optional accessory. The manual describes using a standard 3.5 mm adapter, but its inclusion or exclusion is not explicitly established by the reviewed package list.

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual

Check the exact configuration and source conditions for your use.

Drivers

Nothing CMF Buds 2aCustom 12.4 mm dynamic driver, bio-fibre + custom TPU diaphragm, Dirac tuning
Sennheiser HD 800 S56 mm dynamic ring radiator; 40 mm voice coil; angled drivers, acoustic absorber, vibration-damping chassis and headband insert
Sources
Sennheiser HD 800 S

Manufacturer specification · The driver, diaphragm and voice-coil sizes describe different parts.

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual

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

Wearing style

Nothing CMF Buds 2aIn-ear, true wireless (ear tips in sizes S, M and L)
Sennheiser HD 800 SOver-ear (circumaural), open-back dynamic headphones
Sources
Nothing CMF Buds 2a

Manufacturer specification · A pair of earbuds and a charging case (with a lanyard hole); ear tips in sizes S, M and L are in the box. Nothing does not state the ear tip material.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

Manufacturer specification

Sennheiser HD 800 S — manufacturer specifications

Check the exact configuration and source conditions for your use.

Missing or non-comparable evidence (33)

Acoustic design

Nothing CMF Buds 2aNot verified
Sennheiser HD 800 SOpen-back
Sources
Nothing CMF Buds 2a

No source recorded for this side.

Sennheiser HD 800 S

Manufacturer specification

Sennheiser HD 800 S — manufacturer specifications

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

Active noise cancellation

Nothing CMF Buds 2aYes
Sennheiser HD 800 SNot verified
Sources
Nothing CMF Buds 2a

Manufacturer specification · ANC up to 42 dB (Nothing's laboratory theoretical maximum) over up to 2900 Hz, with Adaptive ANC and Transparency mode.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

The reviewed exact manufacturer sources establish open-back dynamic construction but do not explicitly state whether active noise cancellation is present or absent. Acoustic mesh, an absorber or an omitted ANC control does not establish ANC=false. · Manufacturer specification

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manualSennheiser HD 800 S — manufacturer specification table

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

Microphone

In Visual facts
Nothing CMF Buds 2aYes
Sennheiser HD 800 SNot verified
Sources
Nothing CMF Buds 2a

Manufacturer specification · Four HD microphones in total (two per bud) with Clear Voice Technology and Wind Noise Reduction 2.0.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

The reviewed exact manufacturer sources do not explicitly establish microphone presence or absence for the supplied configuration. Stereo audio conductors and omitted controls are not proof that no microphone exists. · Manufacturer specification

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manualSennheiser HD 800 S — manufacturer specification table

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

Battery life

Nothing CMF Buds 2aEarbuds up to 5 hours with ANC on and 8 hours with ANC off; with the charging case 23 hours with ANC on and 35.5 hours with ANC off.
Sennheiser HD 800 SNot verified
Sources
Nothing CMF Buds 2a

Manufacturer specification · Nothing laboratory results at 25 °C, 50% volume, AAC, other features at default settings; actual life varies with use. Talk time is listed separately (earbuds 3.5 h ANC on / 4 h ANC off; with case 15.6 h / 18.4 h).

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specificationsNothing (US store, us.nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

The reviewed exact manufacturer sources do not explicitly give battery life or state that no battery is required for operation. A wired analogue connection is known; the generic disposal wording “battery/rechargeable battery (if applicable)” establishes neither presence nor absence. · Manufacturer specification

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manualSennheiser HD 800 S — manufacturer specification table

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

Nominal impedance

Nothing CMF Buds 2aNot verified
Sennheiser HD 800 S300 ohm
Sources
Nothing CMF Buds 2a

No source recorded for this side.

Sennheiser HD 800 S

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

Sennheiser HD 800 S — manufacturer specifications

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

Companion app

Nothing CMF Buds 2aNothing X app (Android and iOS): customise equaliser and controls, find my earbuds, low lag mode, software updates
Sennheiser HD 800 SNot verified
Sources
Nothing CMF Buds 2a

Manufacturer specification · Nothing says all these features are available on Nothing OS and in the Nothing X app for iOS and other Android devices (Android 6.0 and above, iOS 13 and above); on Nothing OS 1.5.6 and higher the settings are built into the phone.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specificationsNothing (US store, us.nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

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

Nothing CMF Buds 2aNot verified
Sennheiser HD 800 SDetachable 3 m unbalanced and balanced cables included; XLR-4 cable optional
Sources
Nothing CMF Buds 2a

No source recorded for this side.

Sennheiser HD 800 S

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

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual

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

Charge time

Nothing CMF Buds 2aFull charge (0-100%) in 89 minutes with the case connected to a USB-C cable; with the case unplugged, the earbuds charge inside it in 57 minutes
Sennheiser HD 800 SNot verified
Sources
Nothing CMF Buds 2a

Manufacturer specification · Fast charge: after a 10-minute charge, up to 5.5 hours of playback with the case or 2 hours without it (ANC off, 50% volume, AAC, Nothing laboratory, 25 °C).

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specificationsNothing (US store, us.nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

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

Nothing CMF Buds 2aNot verified
Sennheiser HD 800 S6.35 mm unbalanced cable and 4.4 mm balanced cable
Sources
Nothing CMF Buds 2a

No source recorded for this side.

Sennheiser HD 800 S

Manufacturer specification · Needs a matching headphone output; the 4.4 mm balanced cable needs a balanced output.

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual

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

Rated contact pressure

Nothing CMF Buds 2aNot verified
Sennheiser HD 800 SApproximately 3.4 N ±0.3 N
Sources
Nothing CMF Buds 2a

No source recorded for this side.

Sennheiser HD 800 S

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

Sennheiser HD 800 S — current instruction manual

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

Controls

Nothing CMF Buds 2aTouch controls: double tap to skip forward or answer/hang up calls; triple tap to skip back or reject calls; tap and hold to switch between Active Noise Cancellation and Transparency Mode.
Sennheiser HD 800 SNot verified
Sources
Nothing CMF Buds 2a

Manufacturer specification · Customisable (footnote 7): double tap, triple tap, tap & hold and double tap & hold can be set to next song, previous song, volume up, volume down, voice assistant or switching noise cancellation modes, via phone settings on Nothing OS 1.5.6+ or the Nothing X app on Android 6.0+/iOS 13+.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specificationsNothing (US store, us.nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

No source recorded for this side.

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

Quick pairing

Nothing CMF Buds 2aGoogle Fast Pair and Microsoft Swift Pair
Sennheiser HD 800 SNot verified
Sources
Nothing CMF Buds 2a

Manufacturer specification · Fast Pair works on supported Android devices running Google Play services 11.7+ (back to Android 6.0); Find My and device renaming support need Android 10 or later.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specificationsNothing (US store, us.nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

No source recorded for this side.

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

Frequency equalisation

Nothing CMF Buds 2aNot verified
Sennheiser HD 800 SDiffuse-field equalised
Sources
Nothing CMF Buds 2a

No source recorded for this side.

Sennheiser HD 800 S

Manufacturer specification

Sennheiser HD 800 S — current instruction manual

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

Supplied 3.5 mm adapter

Nothing CMF Buds 2aNot verified
Sennheiser HD 800 SNot verified
Sources
Nothing CMF Buds 2a

No source recorded for this side.

Sennheiser HD 800 S

The manual describes using a standard 3.5 mm adapter but does not explicitly say it is supplied or not supplied. It is absent from the reviewed package list; that omission is not a definitive exclusion. · Manufacturer specification

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual

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

Rated long-term input power

Nothing CMF Buds 2aNot verified
Sennheiser HD 800 SMaximum 500 mW under EN 60-268-7
Sources
Nothing CMF Buds 2a

No source recorded for this side.

Sennheiser HD 800 S

Manufacturer specification · Maximum input the headphones can handle, not the amplifier power they need.

Sennheiser HD 800 S — current instruction manual

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

Low lag mode

Nothing CMF Buds 2a110 ms with a Nothing phone in Game Mode
Sennheiser HD 800 SNot verified
Sources
Nothing CMF Buds 2a

Manufacturer specification · The Other features table says 'less than 110 ms under Game Mode' with a Nothing Phone; footnote 5 says latency can be reduced to as low as 110 ms with Nothing phones and Game Mode on. Source field: Low lag mode.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specificationsNothing (US store, us.nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

No source recorded for this side.

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

Operating temperature

Nothing CMF Buds 2aNot verified
Sennheiser HD 800 S−10 °C to +55 °C
Sources
Nothing CMF Buds 2a

No source recorded for this side.

Sennheiser HD 800 S

Manufacturer specification · Storage −20 °C to +70 °C; relative humidity 10–80% operating and 10–90% storage, non-condensing.

Sennheiser HD 800 S — current instruction manual

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

Rated sensitivity

Nothing CMF Buds 2aNot verified
Sennheiser HD 800 S102 dB SPL at 1 kHz, 1 V rms
Sources
Nothing CMF Buds 2a

No source recorded for this side.

Sennheiser HD 800 S

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

Sennheiser HD 800 S — current instruction manual

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

Replaceable parts

Nothing CMF Buds 2aNot verified
Sennheiser HD 800 SDetachable cables; replaceable ear pads, headband padding and washable 3D-mesh dust covers
Sources
Nothing CMF Buds 2a

No source recorded for this side.

Sennheiser HD 800 S

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

Sennheiser HD 800 S — current instruction manual

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

Sound features

Nothing CMF Buds 2aDirac, Ultra Bass Technology, Custom EQ; tuning by Nothing and Dirac
Sennheiser HD 800 SNot verified
Sources
Nothing CMF Buds 2a

Manufacturer specification · The Sound features table says 'Ultra Bass Technology'; the product copy calls it 'Ultra Bass Technology 2.0'.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specificationsNothing (US store, us.nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

No source recorded for this side.

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

Dust, sweat and water resistance

Nothing CMF Buds 2aIP54 (earbuds)
Sennheiser HD 800 SNot verified
Sources
Nothing CMF Buds 2a

The specification lists 'IPX2 case', but footnote 4 says the IP54 test applies to the earbuds and 'the charging case is not supported'; the case rating is therefore left out. · Manufacturer specification

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

No source recorded for this side.

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

Dimensions

Nothing CMF Buds 2aEach earbud 32.5 x 20.3 x 24.3 mm; charging case 54.7 x 54.7 x 23 mm (height x width x depth)
Sennheiser HD 800 SNot verified
Sources
Sennheiser HD 800 S

No source recorded for this side.

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

Weight

Nothing CMF Buds 2aNot verified
Sennheiser HD 800 S330 g
Sources
Nothing CMF Buds 2a

No source recorded for this side.

Sennheiser HD 800 S

Manufacturer specification · Approximate, without the cable.

Sennheiser HD 800 S — current instruction manual

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.

YOUR CHOICE

Nothing CMF Buds 2a

Select a feature to check your fit.

YOUR CHOICE

Sennheiser HD 800 S

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

Nothing CMF Buds 2a

What it brings

  • They include Adaptive ANC, Transparency mode, dual connection and find my earbuds support.
  • Each earbud weighs 4.28 g and the case 42.75 g, and the case has a lanyard hole for carrying.

What to check

  • Rated playback is 8 hours per charge and 35.5 hours with the case with ANC off, falling to 5 and 23 hours with ANC on.
  • ANC is rated to 42 dB over up to 2900 Hz, calls use four microphones (two per earbud), the listed codecs are AAC and SBC, and the IP54 rating covers the earbuds but not the charging case.

Sennheiser HD 800 S

What it brings

  • Its 56 mm ring-radiator driver is rated 10–44,100 Hz (−3 dB) with total harmonic distortion of 0.02% or less at 1 kHz and 1 V rms, in a diffuse-field-equalised open design.
  • Both a 6.35 mm unbalanced and a 4.4 mm balanced cable are included, and the ear pads, headband padding and dust covers can be replaced by the owner.

What to check

  • At 300 ohms, check that your amplifier or audio source can drive the headphones properly. The documented connection uses the supplied analogue audio cables with 6.35 mm and 4.4 mm plugs.
  • Sennheiser describes the intended use as listening at home with high-quality audio systems. A standard 3.5 mm adapter can be used, but the reviewed sources do not explicitly establish whether one is included.
COMPARE THE DETAILS

Full specifications

How we verify
36 of 36 specifications Sources in each row
Source-backed specifications for Nothing CMF Buds 2a and Sennheiser HD 800 S
SpecificationNothing CMF Buds 2aSennheiser HD 800 S
Wearing styleDifferent
Sources
Nothing CMF Buds 2a

Manufacturer specification · A pair of earbuds and a charging case (with a lanyard hole); ear tips in sizes S, M and L are in the box. Nothing does not state the ear tip material.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

Manufacturer specification

Sennheiser HD 800 S — manufacturer specifications
In-ear, true wireless (ear tips in sizes S, M and L)Over-ear (circumaural), open-back dynamic headphones
Weight per earbud
Sources
Nothing CMF Buds 2a

Manufacturer specification · Each earbud. The charging case weighs 42.75 g.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

No source recorded.

4.28 gNot provided
Each earbud 32.5 x 20.3 x 24.3 mm; charging case 54.7 x 54.7 x 23 mm (height x width x depth)Not provided
Dust, sweat and water resistance
Sources
Nothing CMF Buds 2a

The specification lists 'IPX2 case', but footnote 4 says the IP54 test applies to the earbuds and 'the charging case is not supported'; the case rating is therefore left out. · Manufacturer specification

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

No source recorded.

IP54 (earbuds)Not provided
Acoustic design
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

Manufacturer specification

Sennheiser HD 800 S — manufacturer specifications
Not providedOpen-back
Weight
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

Manufacturer specification · Approximate, without the cable.

Sennheiser HD 800 S — current instruction manual
Not provided330 g
Ear pads
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

Manufacturer specification · Replacement procedure shown in the manual.

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual
Not providedMicrofibre ear pads; replaceable
Replaceable parts
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

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

Sennheiser HD 800 S — current instruction manual
Not providedDetachable cables; replaceable ear pads, headband padding and washable 3D-mesh dust covers
Rated contact pressure
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

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

Sennheiser HD 800 S — current instruction manual
Not providedApproximately 3.4 N ±0.3 N
Wired / wireless connectionsDifferent
Sources
Nothing CMF Buds 2a

Manufacturer specification · The manufacturer lists AAC and SBC codec support; support for other codecs remains unverified. Charging is quoted with a Type-C cable.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

Manufacturer specification · The XLR-4 cable is an optional accessory. The manual describes using a standard 3.5 mm adapter, but its inclusion or exclusion is not explicitly established by the reviewed package list.

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual
Bluetooth 5.4 (AAC, SBC) with dual connection; USB-C charging on the caseWired analogue; detachable 6.35 mm unbalanced and 4.4 mm balanced cables
Battery life
Sources
Nothing CMF Buds 2a

Manufacturer specification · Nothing laboratory results at 25 °C, 50% volume, AAC, other features at default settings; actual life varies with use. Talk time is listed separately (earbuds 3.5 h ANC on / 4 h ANC off; with case 15.6 h / 18.4 h).

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specificationsNothing (US store, us.nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

The reviewed exact manufacturer sources do not explicitly give battery life or state that no battery is required for operation. A wired analogue connection is known; the generic disposal wording “battery/rechargeable battery (if applicable)” establishes neither presence nor absence. · Manufacturer specification

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manualSennheiser HD 800 S — manufacturer specification table
Earbuds up to 5 hours with ANC on and 8 hours with ANC off; with the charging case 23 hours with ANC on and 35.5 hours with ANC off.Not listed by the manufacturer
Charge time
Sources
Nothing CMF Buds 2a

Manufacturer specification · Fast charge: after a 10-minute charge, up to 5.5 hours of playback with the case or 2 hours without it (ANC off, 50% volume, AAC, Nothing laboratory, 25 °C).

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specificationsNothing (US store, us.nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

No source recorded.

Full charge (0-100%) in 89 minutes with the case connected to a USB-C cable; with the case unplugged, the earbuds charge inside it in 57 minutesNot provided
Bluetooth codecs
Sources
Sennheiser HD 800 S

No source recorded.

AAC, SBCNot provided
YesNot provided
Low lag mode
Sources
Nothing CMF Buds 2a

Manufacturer specification · The Other features table says 'less than 110 ms under Game Mode' with a Nothing Phone; footnote 5 says latency can be reduced to as low as 110 ms with Nothing phones and Game Mode on. Source field: Low lag mode.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specificationsNothing (US store, us.nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

No source recorded.

110 ms with a Nothing phone in Game ModeNot provided
Quick pairing
Sources
Nothing CMF Buds 2a

Manufacturer specification · Fast Pair works on supported Android devices running Google Play services 11.7+ (back to Android 6.0); Find My and device renaming support need Android 10 or later.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specificationsNothing (US store, us.nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

No source recorded.

Google Fast Pair and Microsoft Swift PairNot provided
Battery capacity
Sources
Sennheiser HD 800 S

No source recorded.

Earbuds 43 mAh each; case 460 mAhNot provided
Included cable length
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

Manufacturer specification · Length of the supplied cable.

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual
Not provided3 m
Included and optional cables
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

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

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual
Not providedDetachable 3 m unbalanced and balanced cables included; XLR-4 cable optional
Supplied plug configuration
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

Manufacturer specification · Needs a matching headphone output; the 4.4 mm balanced cable needs a balanced output.

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual
Not provided6.35 mm unbalanced cable and 4.4 mm balanced cable
DriversDifferent
Sources
Sennheiser HD 800 S

Manufacturer specification · The driver, diaphragm and voice-coil sizes describe different parts.

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual
Custom 12.4 mm dynamic driver, bio-fibre + custom TPU diaphragm, Dirac tuning56 mm dynamic ring radiator; 40 mm voice coil; angled drivers, acoustic absorber, vibration-damping chassis and headband insert
Sound features
Sources
Nothing CMF Buds 2a

Manufacturer specification · The Sound features table says 'Ultra Bass Technology'; the product copy calls it 'Ultra Bass Technology 2.0'.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specificationsNothing (US store, us.nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

No source recorded.

Dirac, Ultra Bass Technology, Custom EQ; tuning by Nothing and DiracNot provided
Nominal impedance
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

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

Sennheiser HD 800 S — manufacturer specifications
Not provided300 ohm
Driver diameter
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

Manufacturer specification · Ring-radiator transducer diameter.

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual
Not provided56 mm
Rated frequency range
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

Manufacturer specification · The manual gives both thresholds; the UK page lists only the wider range.

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual
Not provided10–44,100 Hz (−3 dB); 4–51,000 Hz (−10 dB)
Rated sensitivity
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

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

Sennheiser HD 800 S — current instruction manual
Not provided102 dB SPL at 1 kHz, 1 V rms
Frequency equalisation
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

Manufacturer specification

Sennheiser HD 800 S — current instruction manual
Not providedDiffuse-field equalised
Rated total harmonic distortion
Sources
Nothing CMF Buds 2a

No source recorded.

Not provided≤0.02% at 1 kHz, 1 V rms
Rated long-term input power
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

Manufacturer specification · Maximum input the headphones can handle, not the amplifier power they need.

Sennheiser HD 800 S — current instruction manual
Not providedMaximum 500 mW under EN 60-268-7
Microphone
Sources
Nothing CMF Buds 2a

Manufacturer specification · Four HD microphones in total (two per bud) with Clear Voice Technology and Wind Noise Reduction 2.0.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

The reviewed exact manufacturer sources do not explicitly establish microphone presence or absence for the supplied configuration. Stereo audio conductors and omitted controls are not proof that no microphone exists. · Manufacturer specification

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manualSennheiser HD 800 S — manufacturer specification table
YesNot listed by the manufacturer
Active noise cancellation
Sources
Nothing CMF Buds 2a

Manufacturer specification · ANC up to 42 dB (Nothing's laboratory theoretical maximum) over up to 2900 Hz, with Adaptive ANC and Transparency mode.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

The reviewed exact manufacturer sources establish open-back dynamic construction but do not explicitly state whether active noise cancellation is present or absent. Acoustic mesh, an absorber or an omitted ANC control does not establish ANC=false. · Manufacturer specification

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manualSennheiser HD 800 S — manufacturer specification table
YesNot listed by the manufacturer
Companion app
Sources
Nothing CMF Buds 2a

Manufacturer specification · Nothing says all these features are available on Nothing OS and in the Nothing X app for iOS and other Android devices (Android 6.0 and above, iOS 13 and above); on Nothing OS 1.5.6 and higher the settings are built into the phone.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specificationsNothing (US store, us.nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

No source recorded.

Nothing X app (Android and iOS): customise equaliser and controls, find my earbuds, low lag mode, software updatesNot provided
Controls
Sources
Nothing CMF Buds 2a

Manufacturer specification · Customisable (footnote 7): double tap, triple tap, tap & hold and double tap & hold can be set to next song, previous song, volume up, volume down, voice assistant or switching noise cancellation modes, via phone settings on Nothing OS 1.5.6+ or the Nothing X app on Android 6.0+/iOS 13+.

Nothing (UK store, nothing.tech) — CMF Buds 2a product page with technical specificationsNothing (US store, us.nothing.tech) — CMF Buds 2a product page with technical specifications
Sennheiser HD 800 S

No source recorded.

Touch controls: double tap to skip forward or answer/hang up calls; triple tap to skip back or reject calls; tap and hold to switch between Active Noise Cancellation and Transparency Mode.Not provided
Static magnetic field at the surface
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

Manufacturer specification · Static magnetic field at the headphone surface.

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual
Not provided10.5 mT
Operating temperature
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

Manufacturer specification · Storage −20 °C to +70 °C; relative humidity 10–80% operating and 10–90% storage, non-condensing.

Sennheiser HD 800 S — current instruction manual
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
Supplied 3.5 mm adapter
Sources
Nothing CMF Buds 2a

No source recorded.

Sennheiser HD 800 S

The manual describes using a standard 3.5 mm adapter but does not explicitly say it is supplied or not supplied. It is absent from the reviewed package list; that omission is not a definitive exclusion. · Manufacturer specification

Sennheiser HD 800 S — manufacturer specificationsSennheiser HD 800 S — current instruction manual
Not providedNot listed by the manufacturer
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