From left: mandolinist Chris Thile, bassist Edgar Meyer, cellist Yo-Yo Ma and fiddler Stuart Duncan. — Photo by Jeremy Cowart

If the ultimate goal in life is to do what you love, then master cellist Yo-Yo Ma has found nirvana. Since picking up his instrument of choice at age 4 in his native Paris, Ma has become one of the most beloved classical musicians of the modern era, earning more than a dozen Grammys, a Presidential Medal of Freedom and a National Medal of Arts.

With more than 70 albums to his credit and a steady schedule of engagements with the world's great orchestras, you'd think now would be the time to ease up on the gas after five decades on the stage. But at age 56, Ma says he's still learning every day and can't see any reason to stop exploring all the nooks and crannies of his beloved instrument of choice, "Petunia," a 278-year-old Italian cello.

Ma gave Petunia quite a workout during the recording of his new album, The Goat Rodeo Sessions, a unique collaboration on bluegrass tunes with fiddler Stuart Duncan, bassist Edgar Meyer and mandolinist Chris Thile.

"I would go further than the hands," the affable Ma says of whether tackling this different and demanding style of music was a means to keep his virtuoso fingers nimble. "Ultimately it's exercising your ears, that's the instrument that tells you what you want to hear and then your fingers do the bidding," he explains from his home in Cambridge, Mass., just before leaving to rehearse with the Boston Symphony.

Thankfully, Ma laughs, all those old stories about how our brains stop developing as we mature don't hold up, something he gladly learned during this latest musical challenge. While he's been friends with Meyer for more than 20 years, Ma said observing and playing with 30-year-old Thile was a revelation.

"He reminds me of a far better version of me," the modest master jokes. "Because he's so amazingly gifted and has so much energy … nothing is unreachable for him."

The pedigrees of the other musicians are quite impressive. Meyer is a respected double bass performer/arranger who has played with Joshua Bell, James Taylor and Bela Fleck over the past 25 years. Duncan is an award-winning bluegrass instrumentalist who has recorded with George Strait and Barbra Streisand. Given this company, Ma says he considered himself as much a student as a master on the project.

To get prepared, Ma went to YouTube, watched old movies and picked Duncan's brain about his work with bluegrass icon Bill Monroe. "I was getting a lesson or many lessons in hearing things and the knowledge behind them," he says, adding that he knows of no other music written for this combination of instruments. (If you're wondering about the album title, the Urban Dictionary defines a "goat rodeo" as a chaotic scenario that "requires about 100 things to go right at once if you intend to walk away from it.")

Ma says after years of hopping from concertos to tangos, minimalist pieces to Spaghetti Western music and blockbuster film scores to jazz, trying his hand at bluegrass didn't feel like a mid-career shake-up, just another step along his colorful, unpredictable path.

"I just heard about this concept of the 'bucket list' for the first time yesterday," he says of the idea that bluegrass was just one more box for him to check off on his diverse roster of accomplishments. "I think as you travel through time you encounter all these sounds … and what those sounds do is make you wonder. To be in that state of wonder is one of the best ways to be when you're alive."