As far back as the HD 580, high-end Sennheiser headphones have inspired generations with their balanced, natural reproduction. Recognized as benchmarks for neutral audiophile sound, the HD 600, HD 650, and HD 660S all share visible and audible DNA with the HD 660S2. The revised coil of the S2, for instance, now matches the 300-ohm impedance of the legendary HD 600 & HD 650. This new coil also provides higher magnetic force and electrical dampening for cleaner impulse response.
The surround is now more compliant, too, dropping the resonant frequency to 70 Hz. Considerable effort also went into optimizing the airflow around the transducer. There’s more sensitivity over the entire frequency spectrum because the magnet´s air gap works more efficiently now. Taken together, these measures result in even greater precision, speed, and resolution — with double the sound pressure at the lowest frequencies.