It's difficult to define the music of the Avett Brothers from Concord. They are a mix of bluegrass, newgrass, gospel, country, rock, classical at times, and even some doo-wop.
Their lyrics are straight from the heart. Never settling for simple, predictable rhymes - they tell their life stories like singing poets.
Maybe that's why they've gotten so popular.
But there are other reasons, as I found out when the Avetts gave me unprecedented and exclusive backstage access -- something you've never seen before -- during a three-night stand hundreds of miles from home.
In downtown St. Louis, Missouri, sits the beautiful, 3,000 seat Peabody Opera House where a sell out crowd awaits.
The performance is at eight. The performers started six hours earlier with a sound check. The long hours are the price for fame.
"We're pretty keen on reminding ourselves we're fortunate, we're privileged but we're not special." said Scott Avett. "We're just products of what we put in. But the hard work is the primary component to making it happen."
In 13 years, The Avett Brothers band has become The Avett Brothers corporation, with a traveling road crew of 23. The road manager is Dane Honeycutt, a high school friend of the Avetts.
"Two years ago, we were in one bus with a trailer, now we're in three trucks, three buses."
The band performs 75 concerts or more a year. It does take a toll.
"You have to sacrifice a lot you have to sacrifice relationships, miss a lot of birthdays, miss funerals, all kinds of things," Seth Avett told WBTV. "We try to keep it as honest as we can."
Sound check turns into a mini concert of two hours.
Afterwards, while the crowd enters the theater, we were able to take a rare visit backstage as the principals tuned voices to tight, blood harmony levels.
"For whatever reason our voices are different just enough that they're coming from the same place and it's been, it's been a great tool for us, something we lean on, depend on."
Starting out 13 years ago, it was Scott on banjo, Seth on guitar and Bob Crawford on bass and fiddle. They added Joe Kwon on cello.
It's an eclectic mix of musicians, so who thought this would work?
"We wanted to zig when everyone else zagged," said Scott Avett.
I asked bassist Bob Crawford what he thinks about before a concert.
"Nerves are good," Crawford said. "Just appreciate this won't last forever."
Then it's show time.
"And over these 13 years a significant portion, a significant part of the story is what these people do for us."
What Avett fans do is jump and sing, both young and old. Many know every word of every song.
"I think a big part of what we do is exploit our journey thru life, the ups and the downs, we exploit our personal lives," Seth Avett said.
Over time, their music has evolved, from a trio of balladeers, to sometimes hard driving guitar.
"We're happy that it's moved, it's progressed," said Scott Avett.
His brother, Seth, chimes in, "We've changed so much as people."
And when the two-and-a-half hours of non-stop entertaining ends, the band has learned to make a quick exit. Not lingering, not partying, just saying goodnight after a long day of work.
But the work never ends.
Currently, while touring, the Avetts are working on a song for a movie. We'll let you know when that comes to fruition.