One of the most influential duos in country music history, Ira and Charlie Louvin brought dextrous, gospel-tinged harmonies into the heart of the genre—mostly ignoring any sort of Nashville vogue in favour of spotlighting their own virtuosic singing. Their biggest hits, despite arriving alongside R&B and rockabilly in the mid-1950s, didn’t have drums; mandolin and mostly acoustic sounds were all it took to supplement their version of what’s known as blood harmony, or the specific blend of the voices of closely related singers. Their signature compositions range from the still-startling gospel tune “The Great Atomic Power” to the romantic, soaring “When I Stop Dreaming”. Perhaps their best-known album—as much for its Ira-designed cover as for the affecting gospel within—is Satan Is Real, with its original song “The Christian Life” later revived by Gram Parsons and The Byrds. “I Don’t Believe You’ve Met My Baby,” their only No. 1 hit, became a country standard covered by Dolly Parton, Jerry Douglas and Alison Krauss.