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.
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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.
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.
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
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
Evidence is missing or conflicting on at least one side. This is not a verified difference.
Manufacturer battery life and conditions
LG BUDSPLUSup to 10 (Earbuds (ANC off & Adaptive EQ off)); up to 7.5 (Adaptive EQ off) (Earbuds (ANC on)); up to 30 (Total (Earbuds+Charging Case))
Sennheiser HD 660S2Not verified
Sources
LG BUDSPLUS
Manufacturer specification · Earbud-only and earbuds-plus-case claims, ANC state and up-to qualifiers remain separate. No combined runtime is represented as a single-charge earbud runtime. Manufacturer section: BATTERY LIFE (HRS). Source field: Earbuds (ANC off & Adaptive EQ off). Manufacturer section: BATTERY LIFE (HRS). Source field: Earbuds (ANC on). Manufacturer section: BATTERY LIFE (HRS). Source field: Total (Earbuds+Charging Case).
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
Evidence is missing or conflicting on at least one side. This is not a verified difference.
Bluetooth version
LG BUDSPLUS5.4
Sennheiser HD 660S2Not verified
Sources
LG BUDSPLUS
Manufacturer specification · Literal manufacturer declarations; Yes, No, counts, versions and component/operating qualifiers are preserved. A missing row establishes no capability or absence. Manufacturer section: CONNECTIVITY. Source field: Bluetooth Version.
Manufacturer claims do not establish independently measured performance, current retailer stock or price. Unlisted specifications remain explicitly unknown.
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.
SBC (yes); AAC (yes); BLE (yes); Google Fast Pair Service (yes); 5.4 (Bluetooth Version); Auracast (yes); Microsoft Swift Pair (yes)
Wired analogue stereo; 1.8 m cables with 6.35 mm unbalanced and 4.4 mm balanced plugs; included 3.5 mm adapter
Manufacturer battery life and conditionsSources
LG BUDSPLUS
Manufacturer specification · Earbud-only and earbuds-plus-case claims, ANC state and up-to qualifiers remain separate. No combined runtime is represented as a single-charge earbud runtime. Manufacturer section: BATTERY LIFE (HRS). Source field: Earbuds (ANC off & Adaptive EQ off). Manufacturer section: BATTERY LIFE (HRS). Source field: Earbuds (ANC on). Manufacturer section: BATTERY LIFE (HRS). Source field: Total (Earbuds+Charging Case).
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
Manufacturer specification · Literal manufacturer declarations; Yes, No, counts, versions and component/operating qualifiers are preserved. A missing row establishes no capability or absence. Manufacturer section: CONNECTIVITY. Source field: Bluetooth Version.
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
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
Over-ear (circumaural) wired gaming headset with detachable boom microphone
Wired / wireless connections
Wired: 2 m PC cable with inline volume and mute, 1.5 m mobile cable with button, Y splitter for separate mic and headphone ports, and a USB external sound card (DAC)
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.