AMY MACDONALD From Scotland comes Amy MacDonald, a fetching 20-year-old lass with a guitar, a strong will, thick eyeliner, and a voice that snaps you to attention. MacDonald is on the rootsier side of pop - more KT Tunstall than Lily Allen - and the '60s aren't exactly her guiding light. Her songwriting themes are universal, but her perspective is decidedly youthful. "Poison Prince" is a salute to forever-in-trouble rocker Pete Doherty, and MacDonald makes her rock-star ambitions clear on "Let's Start a Band": "Give me a stage and I'll be a rock 'n' roll queen/ Your 20th-century cover of a magazine/ Rolling Stone, here I come/ Watch out, everyone/ I'm singing, I'm singing my song." MacDonald's album, "This Is the Life," will be released stateside in August, but she'll preview her songs April 28 with her debut US performance at cozy Great Scott in Allston. We give her a year before she's headlining the Orpheum.