A new audiophile versatility 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.