Sennheiser HD 660S2 High-End Headphones, Wired, Black

Sennheiser HD 660S2 High-End Headphones (Wired, Black)

Hear More, Feel More: Effortless Musicality With Deeper Low-End Insight

If you crave the HD 600-series’ natural timbre but wish for a touch more sub‑bass weight and long-haul comfort, the HD 660S2 is tuned for you. Sennheiser refines its reference lineage with a relaxed, non-fatiguing presentation, deeper extension, and the kind of midrange intimacy that makes vocals and instruments feel strikingly lifelike—without the glare or edge that can cut listening sessions short.

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Why Audiophiles Choose This Product

• Tactile, natural sound
  • Warm‑neutral signature with richer sub‑bass than prior 600‑series models, smooth treble, and the unmistakable midrange presence that defines the line. Expect an easy, non‑fatiguing listen that flatters acoustic, jazz, folk, classic rock, and vocal-centric tracks.
• Engineered for precision
  • A 38 mm dynamic transducer, optimized airflow path, and a powerful vented magnet system reduce distortion and improve sensitivity. Sennheiser also lowered the driver’s resonant frequency from ~110 Hz (original HD 660S) to ~70 Hz for more convincing kick and sub‑bass definition.
• All‑day comfort, built to last
  • At just 260 g with plush velour pads and an ergonomic headband, the HD 660S2 remains remarkably comfortable over long sessions. Made in Ireland with serviceable parts and Sennheiser’s proven 2‑pin detachable cable standard.
• Ready for your rig—now and later
  • Ships with two 1.8 m cables: 6.3 mm (single‑ended) and 4.4 mm (balanced), plus a 6.3‑to‑3.5 mm adapter and a storage pouch. The 300‑ohm load pairs beautifully with dedicated headphone amps/DAC‑amps for scaling potential as your system grows.
• A refined take on a legend
  • The HD 660S2 retains the 600‑series’ coherent imaging and timbre while adding low‑end authority and a more “relaxed” overall feel—an evolution welcomed by many reviewers and enthusiasts of the line.

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What’s Included

• HD 660S2 over‑ear open‑back headphones (300 Ω; dynamic 38 mm driver)
• 1.8 m cable with 6.3 mm (1/4 in) plug; 1.8 m cable with 4.4 mm balanced plug
• 6.3 mm to 3.5 mm (1/8 in) adapter
• Soft carry/storage pouch
• Documentation (Quick Guide, Safety, EU DoC; 2‑year manufacturer warranty)

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Technical Specifications

Specification	Value	Notes
Product Type	Wired (open‑back)	Detachable dual‑entry cables; 6.3 mm SE and 4.4 mm balanced included.
Transducer	38 mm dynamic	Optimized airflow; vented magnet system to minimize distortion.
Impedance	300 Ω	Benefits from a quality headphone amp/DAC‑amp.
Frequency Response	8–41,500 Hz	Extended sub‑bass reach vs. HD 660S.
Sensitivity/SPL	104 dB (1 kHz, 1 Vrms)	Easy to drive to moderate levels; headroom improves with dedicated amplification.
THD	<0.04% (1 kHz, 100 dB)	Low distortion supports clean, resolving playback.
Cables & Connectors	1.8 m 6.3 mm SE; 1.8 m 4.4 mm balanced; 6.3→3.5 mm adapter	Versatile connectivity for desktop stacks, DAPs, and pro gear.
Weight	260 g (without cable)	Lightweight chassis with plush velour pads for comfort.
Country of Origin	Ireland	Precision manufacturing and QC.

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Professional Recognition

• Reviews
  • “A wonderfully relaxed… ridiculously easy listen,” with standout vocals and midrange finesse, though bass control isn’t class‑leading against some rivals.
  • TechRadar calls it “a refined… wired, open‑backed” headphone with neutral, detailed sound and a spacious stage—ideal at home, not for commuting.
  • SoundGuys notes a slightly bassier, smoother take than the original 660S, suiting listeners who dislike treble emphasis.
  • WIRED praises the deeper bass extension and expansive staging while acknowledging the higher‑impedance design benefits from a good amp.
• Community feedback
  • Long‑running Head‑Fi owner threads describe the S2 as a relaxed, enjoyable evolution of the 600‑series—some highlight excellent drum impact, others debate value versus planar competitors.
• Heritage & innovation
  • Designed in Germany, made in Ireland, the S2 celebrates Sennheiser’s 600‑series legacy with driver and airflow updates that drop the resonant frequency to ~70 Hz for more convincing sub‑bass.
  • As of September 2025, it remains a recommended mid‑range wired pick in major buyer’s guides.

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The Bottom Line

If you want the HD 600‑series’ famed naturalness, clarity, and comfort—now with more convincing low‑end reach—the HD 660S2 delivers. Its warm‑neutral tuning, low distortion, and fatigue‑free presentation make it a superb “daily driver” for serious listening at home. Give it a clean source and a capable amp, and it rewards you with coherent imaging, lifelike midrange, and newfound sub‑bass depth—hallmarks of a modern classic done right.

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Notes for headphone buyers

• Connectivity: Wired, open‑back over‑ear (not noise‑isolating; designed for quiet spaces).
• Amplification: With 300 Ω impedance, a quality headphone amp/DAC‑amp is recommended to realize full dynamics and control.
• Sound signature: Warm‑neutral with extended sub‑bass, smooth highs, intimate mids.
• Comfort: 260 g with velour pads and ergonomic headband supports extended sessions.

This description is based on official specifications, manufacturer documentation, and professional reviews to ensure accuracy and buyer confidence.