Sennheiser HD 660S2 Wired Open-Back Audiophile Over-Ear Headphones - Black

The Sennheiser HD 660S2 are wired open-back audiophile over-ear headphones made for long listening sessions at home. Sennheiser launched them in February 2023 as the next step after the HD 660S, and they belong to the same family as the HD 600 and HD 650. The tuning is warm and relaxed, with smooth treble and more weight in the lowest bass. Sennheiser says the changes double the sound pressure in the lowest octave, so the bottom note of a piano at 27.5 Hz or a kick drum comes through with real body. It lists an 8 Hz to 41.5 kHz response, 300 ohm impedance, 104 dB SPL and distortion of 0.04 percent or less.

Each ear cup holds a 38 mm dynamic driver with an ultra-light aluminium voice coil and a vented magnet system, with milled air vents in the magnet yoke to keep distortion down. A softer surround lowers the driver's resonance from 110 Hz on the HD 660S to 70 Hz, and steel mesh damping shaped to the driver controls the airflow. Velour ear pads and a padded headband keep the weight of about 260 g, without the cable, comfortable for hours. The finish is black with bronze accents. Sennheiser designs the HD 660S2 in Germany and makes them in Ireland. Two detachable 1.8 m cables come in the box, one with a 6.35 mm plug and one with a balanced 4.4 mm plug.

At 300 ohm the HD 660S2 need a headphone amplifier or a DAC with a strong headphone output to sound their best, and a phone or laptop socket may not drive them loud or clean enough. Being open-backed, they let outside sound in and let people nearby hear your music, so they suit a quiet room more than travel or the office. There is no microphone, remote or noise cancelling, and an XLR-4 balanced cable is sold separately.

Choose the cable for your source: the 6.35 mm cable for an amplifier or receiver with a standard headphone socket (fit the adapter for a 3.5 mm socket), or the 4.4 mm cable for a balanced output. Plug the cable into the ear cups, matching the L and R marks on the connectors with the ear cups, and push each connector in firmly. Turn the volume down before you plug in, put the headphones on with the L and R marks on the correct sides, and adjust the headband until the ear cups sit comfortably around your ears. To swap cables, pull the connectors straight out of the ear cups. To change the ear pads, pull them off the ear cups and press the new ones on until they click into place. Clean the headphones only with a soft, dry cloth, keep them in the pouch when not in use, and do not leave them on a dummy head or chair arm for long, as this can widen the headband.

Sennheiser HD 660S2 headphones, detachable 1.8 m cable with a 6.35 mm stereo plug, detachable 1.8 m balanced cable with a 4.4 mm plug, 6.35 mm to 3.5 mm stereo adapter, storage pouch, quick guide and safety guide. No XLR-4 cable or headphone amplifier is included.

Sennheiser gives the first owner a two-year warranty from the date on the invoice when this product is bought new from an authorised Sennheiser dealer in India. A defect in materials or workmanship in that period is repaired, or the product or faulty part replaced, free of charge at Sennheiser's choice. To claim, contact Sennheiser India customer support or visit a Sennheiser service centre with the original invoice, as every claim needs it. The detachable cables, the adapter and other accessories in the box, the ear pads, normal wear and tear, damage from misuse or accidents, and products opened or repaired by anyone other than an authorised service partner are not covered.