From the manufacturer
Sennheiser is shaping the Future of Audio – a vision built on a 75-year history of innovation and a continued drive for excellence that is woven into our company’s DNA and culture. Around the world, our employees share this passion in the pursuit of the perfect sound, creating products that exceed expectations and set new benchmarks in audio.
Meet the Sennheiser HD 660 S
The new HD 660 S is the successor to the legendary HD 650. This open-back, dynamic headphone features new lower (150-ohm) impedance transducers producing reference-class sound when connected to both Hi-Res home or mobile audio systems. An elegantly designed piece of German engineering, the HD 660 S delivers exceptionally accurate and transparent sound, with an expressiveness that immerses the listener in every emotion and nuance of the music.
Did you know? The HD 660 S is designed and engineered in Germany, then manufactured to exacting standards in Sennheiser’s Tulamore, Ireland factory.
Every HD 660 S undergoes rigorous, multi-parameter testing to insure performance essential to the most demanding listeners.
Crafted for the demanding listener, the HD 660 S surpasses the performance of its predecessor, the legendary HD 650. Detailed and dynamic, with extended and balanced frequency response, the HD 660 S is exceptionally accurate and musically expressive. The lower 150-ohm impedance facilitates direct connection to both premium home and mobile audio devices.
The HD 660 S employs newly designed transducers featuring extremely lightweight aluminum voice coils coupled to diaphragms precision-crafted from stainless steel fabric. This combination results in exceptional transient response and improved control of diaphragm movement reducing distortion. Additionally, transducers are produced and matched to extremely tight (± 1 dB) tolerance ensuring superb performance.
The HD 660 S is supplied with two para-aramid reinforced detachable cables employing high conductivity OFC copper to ensure signal integrity with very low handling noise. One cable is terminated with a 6.35mm stereo plug (a 3.5mm adaptor is also included), the other with the new 4.4 mm Pentaconn balanced stereo plug. Balanced connectivity can reveal full HD 660 S performance potential when paired with the balanced output of a digital audio player or headphone amplifier like the Sennheiser HDV 820.
The HD 660 S is designed for pure listening pleasure. Its open-back architecture is strong yet lightweight and allows airflow to the ears, keeping them cool during listening sessions. The large elliptical ear cups are shaped following the anatomy of the ear, and feature soft velour covered ear cushions. Thick headband padding completes the comfort package to provide hours and hours of supreme listening pleasure.
HD 660 S
10 – 41,000 Hz (-10 dB), Diffuse-field equalized
10 – 41,000 Hz
12 – 40,500 Hz
8 – 44,000 Hz (-10 dB), Diffuse-field equalized
Sound Pressure Level (SPL)
104 dB (1 kHz / 1 Vrms)
103 dB (1 kHz / 1 Vrms)
93 dB (1 kHz / 1 Vrms)
105 dB (1 kHz / 1 Vrms)
Total Harmonic Distortion and Noise (THD + N)
<0.04% (1 kHz, 100 dB)
<0.05% (1 kHz, 100 dB)
<0.01% (1 kHz, 100 dB)
<0.03% (1 kHz, 100 dB)
6.35 mm / 4.4 mm Pentaconn
3.5 / 6.3 mm Stereo
¼” (6.3 mm) Stereo
Weight w/o Cable
9.17 oz. (260 g)
9.17 oz. (260 g)
9.17 oz. (260 g)
9.52 oz. (270 g)
In the Box
HD 660 S / Cable with 6.35 mm Plug / Cable with 4.4 mm Pentaconn Plug (balanced) / Adapter 6.35 to 3.5 mm / Manual / Storage Box
HD 650 / Cable with 6.35 mm Plug / Adapter 6.35 to 3.5 mm / Manual / Storage Box
HD 600 / Cable with 6.35 mm Plug / Adapter 6.35 to 3.5 mm / Manual / Storage Box
HD 700 / Cable with 6.35 mm Plug / Manual / Storage Box
Reference class open back, dynamic headphone employing new and improved transducers delivering low harmonic distortion
Transducers are hand selected for precise (1 dB) left / right matching tolerance insure exceptional accuracy and presentation of stereo spatial characteristics
150 ohm nominal impedance allows direct connection to home and mobile Hires audio devices. Contact pressure: 6.0 N – 1 N
Para aramid reinforced, detachable cables employ high conductive OFC copper to insure signal integrity with very low handling noise
Supplied with two connection cables: One with a 6.35 millimeter stereo plug, the other a 4.4 millimeter Pentaconn balanced stereo plug. Also included is a 6.35 millimeter to 3.5 millimeter adaptor. Connectivity Technology: Wired 6.35 millimeter / 4.4 millimeter Pentaconn
Frequency response 10 to 41,000 Hz ( 10 dB), Impedance 150 ohm
Note: Kindly refer to the user manual provided as a PDF manual in the product description section