The folked-out rock and popped-up bluegrass of Nickel Creek ain’t just pretty — we’re talkin’ whiplash, drool, wolf-whistle gorgeous. Naturally, bluegrass purists hate it with an intensity once reserved for electric fiddles and the wah-wah pedal. But open-eared listeners want to lick it all over. The mandolin, fiddle and guitar trio double-fists influences from, well, everywhere. Note their formation of the Mutual Admiration Society with the dude from Toad the Wet Sprocket. Siblings Sara and Sean Watkins have been playing with Chris Thile for more than 13 years, a partnership that has bred the kind of effortless familiarity that bands usually achieve right before they qualify for the senior-citizen discount at IHOP. Nickel Creek is decades ahead of the curve — though we bet the waitress will still probably knock a few bucks off their Rooty Tooty Fresh and Fruity.