Sennheiser HD 660S2 – open-back dynamic over-ear headphones with 38 mm transducers, 300 Ω impedance, 104 dB SPL (1 kHz/1 Vrms), 8–41,500 Hz frequency response, <0.04% THD (1 kHz/100 dB), 260 g weight, detachable 1.8 m cables (6.3 mm single-ended and 4.4 mm balanced), 6.3–3.5 mm adapter, made in Ireland.
HD 660S2 refines the HD 600-series reference tuning with deeper sub-bass extension and improved airflow around the driver for higher acoustic efficiency. An ultra-light aluminum voice coil with a 300-ohm load delivers fast transient response and low distortion, while the open-back chassis preserves a wide, natural soundstage.
The driver assembly uses steel-mesh damping shaped to the transducer geometry and a vented magnet system to control air movement and minimize distortion. Plush velour pads and a low-mass headband provide long-session comfort, and the dual detachable cables (single-ended and 4.4 mm balanced) simplify integration with studio and hi-fi headphone amps.
KEY FEATURES
- 300 Ω ultra-light aluminum voice coil for precise transients and amplifier synergy
- 38 mm dynamic transducers with optimized surround and airflow for extended sub-bass
- Open-back architecture for natural imaging and spacious soundstage
- Vented magnet system and steel-mesh damping to reduce distortion
- Two detachable 1.8 m cables (6.3 mm and 4.4 mm) plus 6.3→3.5 mm adapter
- Plush velour earpads; replaceable pads and cables for long-term serviceability
- Manufactured in Ireland
TECHNICAL SPECIFICATIONS
- Transducer principle: Dynamic, open
- Transducer size: 38 mm
- Impedance: 300 Ω
- Frequency response: 8 – 41,500 Hz
- Sound pressure level (SPL): 104 dB (1 kHz, 1 Vrms)
- Total harmonic distortion (THD): <0.04% (1 kHz, 100 dB)
- Ear coupling: Over-ear
- Weight (without cable): 260 g
- Cable length: 1.8 m (both)
- Connectors: 6.3 mm (single-ended), 4.4 mm (balanced)
- Included: HD 660S2 headphones, 6.3 mm cable (1.8 m), 4.4 mm balanced cable (1.8 m), 6.3→3.5 mm adapter, pouch
- Country of origin: Ireland
