Sennheiser HD 660S2 Open-Back Headphones – Black

The Sennheiser HD 660S2 is a wired, open-back over-ear headphone with 38 mm dynamic transducers and 300-ohm impedance. The design refines the earlier HD 660 series with revised airflow and voice-coil construction, with the manufacturer describing extended sub-bass performance. This is not a headphone whose bass response stops at 70 Hz: the published frequency range is 8 Hz to 41.5 kHz. Open earcups allow sound leakage and do not provide closed-back isolation, so a quieter room is preferable. Detachable cable arrangements support 6.35 mm single-ended and 4.4 mm balanced connections, with a suitable source required for whichever output you choose. A capable headphone output is advisable for the 300-ohm load; no amplifier is included. The listing is the Black S2 version, not the original HD 660S.