This is the newly updated version of the legendary Sennheiser HD660 headphone. There are several refinements across the frequency spectrum versus the previous generation but bass response is the most notable improvement from the older to the newer S2 generation.

These are open back headphones so sound will leak in and out to some degree so they are best suited to a quieter listening environment. They are somewhat demanding on the quality of headphone amplifier being used but are still flexible enough to work with many lower powered headphone outputs.

These also include upgraded balanced cables in the box which can give you better overall performance if your headphone amplifier has a balanced headphone output.

HD660S2 Specifications

• Transducer principle: dynamic, open

• Transducer size: 38 mm

• Frequency response: 8 – 41,500 Hz

• Impedance: 300 Ω

• 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: 260g

• Adapter: 6.3 mm (1⁄4 inch) to 3.5 mm

• Connector: 6.3 mm (1⁄4 inch) jack plug, 4.4 mm balanced plug

• Cable length: 1.8m