>In the studio, John Mayer comes across as a technically proficient singer, songwriter and guitarist, although he can sound somewhat emotionally removed from his material. But on this two-disc live CD set (a DVD is sold separately), he proves he’s not just another easy-listening singer-songwriter with a better-than-average knack for the blues. The album features three separate acts — acoustic folk, power-trio blues and full-band rock — and Mayer lets his guitar go anarchic on each one. It’s clear that he’s really feeling the music when he launches into the protest R&B of his 2006 hit “Waiting on the World to Change,” and when he quotes a few bars of Otis Redding’s “I’ve Got Dreams to Remember” before segueing into his own soulful “Gravity.” Groupies will swoon over the opening five-song acoustic set of lightweight favorites like “Daughters,” but it’s when Mayer trots out the power trio that his blues licks get red-hot, peaking with the squalling, 10-minute guitar workout “Out of My Mind,” where he conjures Hendrix not just in the riffage but also in the question he asks his audience midway into the song: “Can I play my GIT-tar? Can I play it loud?” Easy listening? Not this set.