The new HD 660 S lets you enjoy sophisticated audiophile sound in even more listening situations. The successor of the legendary HD 650 excels with the improved performance of its new transducer design. Thanks to its lower impedance, it delivers reference-class sound also when connected to hi-res mobile players, thus offering much greater versatility. The HD 660 S is an elegantly designed piece of high-quality engineering that indulges the demanding listener with aural precision and great wearing comfort.

The HD 660 S features a new transducer design developed by Sennheiser. This results in improved control of the diaphragm movements thanks to a specially manufactured precision stainless steel fabric, which is adapted to the contour of the diaphragm. Extremely light aluminum voice coils ensure the highest impulse fidelity. The transducers are carefully selected and paired by hand to ensure consistently narrow (±1 dB) tolerances.

The HD 660 S has been created to enjoy music in supreme quality and from many different audio sources. Thanks to its low impedance it also offers reference-class fidelity with hi-res mobile players. Naturally, the HD 660 S reveals its full potential when it is connected to the balanced outputs of a dedicated headphone amplifier such as the HDV 820 or to the balanced output of a mobile digital audio player. Accordingly, it comes with a choice of cables for just about any occasion. All cables are made of highly conductive OFC copper, featuring very low handling noise and sturdy reinforcement.

Our Take

The HD660S delivers a higher level of performance than ever before, from that same familiar, comfortable structure that headphone audiophiles have known for decades, from the HD580, HD600, and HD650.  For the first time in this line, Sennheiser has included a balanced cable in the package, in the 4.4mm pentaconn format.  No doubt, the HD660S is a prime contender for the title of best sounding headphones under $500, and like their ancestors, they benefit strongly from amplification, making a great pairing with the new HeadAmp Gilmore Lite mk2.