Nickel Creek fans should get a big dose of new — and potentially surprising — music at this large-venue showcase. The trio’s recently released This Side kicks off with slinky newgrass, but just when you think they’ve gone Grisman, the next tune is a Pavement cover. Nickel Creek, still a young, not-quite-bluegrass group, is just throwing down the stuff that makes it happy. Fiddler/singer Sara Watkins, whose rendition of “Reasons Why” moved the band to the front of the new-acoustic pack, still has one of the loveliest voices in the genre. With two young songwriters (mandolinist Chris Thile and guitarist Sean Watkins) and the ability to blend bluegrass, folk, Celtic and pop, Nickel Creek follows the trail gently blazed by Alison Krauss (who produced This Side). Nickel Creek plays music that’s often just plain beautiful, for which it has received its share of detractors. Still, its members have way more talent than three people oughta have — and if they use it to make gorgeous music … well, they do.