The new Sennheiser HD 660S2 offers listeners what they requested most from the headphones’ predecessor,” says Jermo Koehnke, Sennheiser Audiophile Product Manager. “With precision and power like no other and new sensitivity across all frequencies, listeners will hear details they’ve never heard before, especially at the lower end of the spectrum.”

The depth and drama audiophiles crave

​Improving on a beloved classic while retaining its best traits was a challenging task, starting with the lowest end of the frequency plot. The HD 660S2's warm bass characteristics pair perfectly with its silky-smooth treble performance and trademark vocal presence, allowing the timbre and uniqueness of any instrument part to stand out.

Across the entire frequency spectrum, the HD 660S2 delivers a refined listening experience thanks to improved transducer airflow and a refined voice coil. From thunderous timpani crescendos to pulsating EDM rises, even the most discerning audiophiles will notice the depth and nuance of low-frequency passages, adding dramatic flair to any type of music. Ultimately, listeners are treated to deeper, clearer bass without sacrificing the expansive detail the series is known for. By reducing the voice coil's weight, impulse response improves, bringing hyper-realistic textures to the forefront of any performance reproduction. The overall experience is smoother and warmer than the original HD 660S, thanks to ​ that reduces the distances between select peaks and troughs. The overall impedance matches that of the HD 600 and HD 650, at an audiophile-friendly 300 ohms, for punchy dynamics and impressively low distortion.

A fit for the long haul

​Designed in Germany and manufactured at Sennheiser's state-of-the-art Ireland production facility, the HD 660S2 continues the series' emphasis on quality, functional design using materials that contribute to the hi-fi experience. Plush earpads and cushy headband padding place the revised 300-ohm transducers at the optimal distance from the ear resulting in a spacious soundstage with an abundance of detail -- even for extended musical exploration. The transducer surround drops the resonant frequency from 110 Hz (original HD 660S) down to 70 Hz for hefty kick drums that move with ease. Even the outer mesh grilles are crafted to manage airflow at the ideal impedance for exquisite open-back listening sessions.

Versatile enough to connect to vintage classics and modern solutions alike, the HD 660S2 ships with two 1.8 meter (5.8 ft) user-detachable cables that terminate to 6.3 mm (1/4-inch) single-ended stereo and 4.4 mm balanced stereo jack plugs, respectively. A 6.3 mm to 3.5 mm (1/8-inch) adapter is also included, for use with popular hi-fi gear from DAC-amps, DAPs, and dedicated amplifiers such as the Sennheiser HDV 820. Distinguishing bronze accents complement the elegant jet-black finish, all of which is protected by a storage pouch.

• Impedance: 300 Ω

• Connector: Stereo jack plug, gold-plated 6.35 mm, unbalanced, 3-pin 4.4 mm, balanced, 5-pin

• Frequency response: 8 – 41,500 Hz (-10 dB) 

• Sound pressure level (SPL): 104 dB at 1V 1kHz

• Ear coupling: Over-ear (circumaural) 

• THD + N, total harmonic distortion and noise: < 0,04% (1 kHz, 100 dB) 

• Transducer principle (headphones): Dynamic, open

• Weight w/o cable: Approx. 260 g (without cable) 

• Made in Ireland

• Woo Audio is an authorized reseller

• HD 660S2 headphone x 1

• 1.8m, 4.4mm Balanced cable x 1

• 1.8m, 1/4" TRS cable x 1

• 1/4" to 3.5mm adapter x 1

• Storage pouch x 1