Ultimate connectivity
The HD 660 S has been designed to enjoy music in superior quality from many different audio sources. Thanks to its low impedance, it also offers the class-leading fidelity of high-resolution mobile players. Naturally, the Sennheiser HD 660 S reveals its full potential when connected to the balanced outputs of a dedicated headphone amplifier, such as the HDV 820 (sold separately), or to the balanced output of a portable digital audio player. As a result, Sennheiser has thought of everything, and it comes with a wide range of cables to suit almost any situation. All cables are made of highly conductive OFC copper, with robust para-aramid fibre reinforcement.