"I love his latest record," Prine told the Los Angeles Times on Monday during an interview at his hotel in Hollywood, referring to Simpson's widely praised "A Sailor's Guide to Earth" album released in April.
"He's been using the same [Nashville] studio where I have some space, and one day he'd be in there with a steel guitar playing country, the next day he'd have those great R&B horns. Another day he brought in a Moog synthesizer."
So when Prine, 69, was invited by Grammy Museum officials to talk about his career and give musical examples for its Up Close & Personal series, "They asked me if I wanted to invite someone else to come along, and I said Sturgill. He said he would, as long as all we play is John Prine songs."
Their 7:30 p.m. Pacific time session will live-stream on the Grammy Museum's website.
Prine has been cited as a key influence on a raft of emerging singers and songwriters, including Simpson, Chris Stapleton, Jason Isbell (with whom he just wrapped up a tour that played the Greek Theatre), Kacey Musgraves, Brandy Clark and even country superstar Miranda Lambert.
Lambert recorded Prine's song "That's the Way the World Goes 'Round" on her 2009 album "Revolution" and has often said her parents played his music regularly at home when she was growing up in Texas.
"She was on an award show where she took just about every award except male vocalist, and when they asked her what song she was going to sing, she said 'That's the Way the World Goes 'Round," Prine said. "That's when I thought, 'I like this girl.' Usually they want you to push your latest single on those shows."
Prine is best known for exquisitely nuanced songs such as "Hello in There," about the loneliness of aging; "Sam Stone," about a drug-addicted Vietnam war vet's struggle after returning home; and "Paradise," about coal companies that often decimate the land around them.
He's also written brilliantly witty lighter fare such as "Illegal Smile," his 45-year-old ode to the joys of lighting up, and the poignant "Linda Goes to Mars," chronicling a man whose wife tunes him out when he comes home from work at night.
That says nothing, of course, about how he's been something of a pioneer in the music business, launching his own record label, Oh Boy Records, in the early 1980s as a way for a musician who wasn't routinely churning out platinum-selling albums to make a living playing music.
In the coming weeks, Calendar will have a more in-depth feature about Prine's musical legacy, his struggles through two bouts of cancer treatment and what is ahead.
Looking immediately toward Tuesday night's Grammy Museum event, he said, "I've just had lunch with him once, and I figure this is going to be great way to spend some more time with him."
Follow @RandyLewis2 on Twitter.com