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 - 8 April 2022 42 0 SHARE Facebook Twitter Go to the deal page: Sennheiser HD 660 S Open-Back Audiophile Headphone $299 + free s/h at Adorama