The new model, a follow-up to the audiophile favourite HD 650, features improved transducers and lower impedance.
The new model is the successor to the widely-respected HD 650, which has been a favourite of producers and engineers for 14 years. Aesthetically, the HD 660 S retains the open-back design and sliding headband of its predecessor, but features a new transducer that promises a total harmonic distortion level of <0.04%—a percentile better than the HD 650. Each transducer is paired by hand to keep the frequency response of the left and right cups within a single decibel. The impedance level has also been lowered from 300 to 150 Ohms, meaning the headphones can be powered without a headphone amplifier.
Read our feature on the industry standard Sennheiser HD 25 headphones.
The Sennheiser HD 660 S is available now for US $499.95.