Home Headphones Sennheiser HD 660S2 Sennheiser
Released February 2023
The HD 660S2 are Sennheiser's open-back wired headphones from the HD 600 series, retuned with more sub-bass than the HD 660S, suited to home listeners with a headphone amplifier.
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MDR-R10 (1988) MDR-V6 (1985) Arctis Nova Pro Omni (2026) Arctis Nova 5 Wireless (2024) EAH-AZ100 (2025) Model history · 2 models, 2017–2023 2017 HD 660S Compare 2023 HD 660S2
Type Over-ear
Noise cancelling No
Battery –
With case –
Best codec Wired
Weight 260 g What reviewers say Reviewers agree the sound is neutral, clear and easy to listen to, with a little more bass than the HD 660S, and that the headphones are comfortable. SoundGuys found them too close to cheaper Sennheisers to justify the price, TechRadar noted they need a separate amplifier to sound their best, and Headfonics found the clamping pressure high when new.
From soundstagesolo.com , techradar.com , soundguys.com and headfonics.com
Sound
Type Over-ear
Noise cancelling No
Driver size 38 mm
Back Open
Impedance 300 ohms
Bluetooth codecs None (wired)
Drivers Dynamic, open; 8 – 41,500 Hz; 104 dB SPL (1 kHz, 1 Vrms); THD < 0.04% (1 kHz, 100 dB); lighter voice coil than the HD 660S, with the transducer's resonant frequency lowered from 110 Hz to 70 Hz Battery
Listening time (maker's claim) No battery (wired) Design
Weight 260 g
Headphone cable Yes
Fit and ear tips Over-ear (circumaural), open-back
Works with Detachable 1.8 m cables with a 6.3 mm plug and a balanced 4.4 mm plug; 6.3 mm to 3.5 mm adapter
In the box HD 660S2 headphones, 1.8 m cable with 6.3 mm plug, 1.8 m cable with 4.4 mm balanced plug, 6.3 mm to 3.5 mm adapter, carry pouch Pros and cons Pros + 8 Hz to 41.5 kHz frequency response with THD below 0.04%+ Both 6.3 mm and balanced 4.4 mm cables in the box+ Light at 260 gCons − 300-ohm impedance calls for a capable headphone amplifier− Open back leaks sound and lets outside noise inPrevious model: HD 660S .
