Which one of the five women onstage is Della Mae? Philosophers could argue for a good while between the answers "all" and "none."

But for audiences, "Della Mae"--technically, the Boston Bluegrass group's second name--is a clue both to their impromptu origins and their musical tastes. In the first place,Bostonis not exactly a hotbed of Bluegrassmusic.

But Kimber Ludiker, a native of Spokane Valley and daughter of a veteran fiddle champion, was at a music camp with some friends when she remarked that they should start an all-female band that played only high-testosterone Bluegrass numbers, which their inside joke categorized as "Mangrass."

To prove it could be done, they did it--naming themselves after an Osborne Brothers song, "Big Spike Hammer." And for stylistic emphasis, they played onstage in power business suits and high heels. And they pronounced it a lot of fun. Then, the mood changed: they decided to set aside the original gimmick, and take themselves seriously as musicians.

Their first step was to find a new name. Fortunately, one was close at hand--in the chorus of "Big Spike Hammer," with its line, "Hey, hey, Della Mae / Why do you treat me this-a-way?" In the years since, the fivesome (with several shifts in personnel) has earned a reputation for, as one critic says, "virtuosic modernBluegrasswith a broad appeal"--and writing much of their own material as well.

And while their adopted hometown ofBostonstill isn't aBluegrassmecca, the members view it as an acoustic wonderland for a little bit of every genre. Example: this summer, in the same week, Della Mae played at the Lizard Lounge, Club Passim, and Middle East Upstairs.

"I like the concept of a band doingBluegrassfestivals and rock clubs in the same weekend," says Bryan Sutton, a longtime friend of the group and producer of their newest album. "There’s a movement across the country that’s reflected a little bit in the bigger commercial bands like the Lumineers and Mumford & Sons. But it also filters into a lot of the energy of bands like Della Mae and Punch Brothers.”

This past year they signed with big-label Rounder Records, and their new album, their second full-length one, is "This World Oft Can Be." One reviewer calls it "a merry, genteel collection of old-fashionedBluegrass, folk, and country, that beautifully showcases Della Mae's all-female harmonies."

"One of the challenges we had was going into the studio with a brand-new lineup," says producer Sutton. But on the upside, "It didn't seem like roles were so defined yet--this person picks the songs, this person does the solos. Usually bands work that out after a while, but with Della Mae it was a clean slate. Everybody was just excited about being there, and I enjoyed seeing the potential that was there, and working with it."

Della Mae's current personnel, in addition to founder Ludiker, are Celia Woodsmith (vocalist and a primary songwriter), Courtney Hartman (guitar), Shelby Means (bass), and Jenni Lyn Gardner (mandolin). Band members say they're still proud of their first CD, "I Built This Heart," from 2011, but that the newer one is "a more accurate portrait of a fully formed band."

“I think there are a lot of differences [with the new CD], both subtle and pretty noticeable,” says Woodsmith, who wrote 10 of the first album's songs. “This new record is more of a collective group effort. We really worked hard together on these songs and came up with our sound, which had been building over a couple of years. There’s a lot of different influences on it, but it’s us. It’s finally who we are.”

A free MP3 download is available, of the single "Empire" from Della Mae's new Rounder Records album "This World Oft Can Be."   Click here for free download.