Strip it bare. Find the essence, the core, the soul of a song and record it before you die. Rick Rubin's production efforts on the American Recordings series does this flawlessly for the twilight of Johnny Cash's career.
As Wikipedia put the backstory,
.... Although he was no longer sought after by major labels, Cash was approached by producer Rick Rubin and offered a contract with Rubin's American Recordings label, better known for rap and hard rock than for country music. Under Rubin's supervision, he recorded the album American Recordings (1994) in his living room, accompanied only by his guitar. The album featured several covers of contemporary artists selected by Rubin, and saw much critical and commercial success .... Cash released a sequel, Unchained , and enlisted the accompaniment of Tom Petty and the Heartbreakers. ... [In 1997, serious illness] forced Cash to curtail his touring. He was hospitalized in 1998 with severe pneumonia, which damaged his lungs. The albums American III: Solitary Man (2000) and American IV: The Man Comes Around (2002) contained Cash's response to his illness ....These albums are digital gold (this review covers the 1st four of the five album series).
Take the unnerving, brutal realism of "Delia's Gone". As with Willy Nelson's "I Just Can't Let You Say Good-Bye", Cash explores the darker side of love where the timid simply will not tread.
With "The Man Who Couldn't Cry", Cash delivers a hard-edged parable that made me feel like I was listening to a secular preacher.
Unchained (1996) is an eclectic set of covers mixed with superb Cash originals. Add Tom Petty & The Heartbreakers as the back-up band and you have the perfect crossover album.
Two more thoughts and I'll wrap this up. I got an 80 minute, 24 song sampler of these 4 albums from my godson -- he's on the verge of turning 30. My chronic fears about the pop dung young people listen to today are now gone. I've been working as a song-miner for 40 years, but the next generation's safe if they can turn me on to material this good.
Finally, one song from this album series does something rare: what Jimi Hendrix did with Dylan's "All Along the Watchtower", what SRV did with Jimi's "Little Wing": covering another outstanding singer/songwriter's original and making the cover version definitive, the best version of the song ever done. I stand here to testify that Johnny Cash's cover of U2's "One", from American III: Solitary Man, is the definitive version of this song. I can't believe I'm writing this, but Bono, Edge, Adam, Larry, sit down and take notes. The Man in Black has stolen this song from you. From now on, for me, "One" is a Johnny Cash song that U2 wrote and popularized.