Home Slickdeals Sennheiser HD 660 S Open-Back Audiophile Headphone $299 + free s/h at... Slickdeals Sennheiser HD 660 S Open-Back Audiophile Headphone $299 + free s/h at Adorama By ARCOM - 26 March 2022 58 0 SHARE Facebook Twitter Go to the deal page: Sennheiser HD 660 S Open-Back Audiophile Headphone $299 + free s/h at Adorama