On his BBC Radio 6 show last night, UK producer Mark Ronson spun a previously-unreleased demo of Amy Winehouse’s trademark song “Back to Black” (Ronson co-produced the eponymous 2006 breakthrough LP). Though unmastered and without the album version’s post-production kick, the cut still showcases the amazing power of Winehouse’s voice as an unending wealth of profound beauty and life-affirming heartache. Stream it now at Okayplayer.