Don't bother with earplugs---Davis Guggenheim's music doc It Might Get Loud, playing Friday and Saturday at midnight, never hits 11. This is surprising, considering that An Inconvenient Truth was a world-altering film. No pressure, dude. The idea is rock-solid: three generations of guitar rock heroes---Jimmy Page, The Edge and Jack White---muse on their careers, inspirations and instruments (there's lots of Les Paul stroking). But the majority is spent on autobiographical details, and while it's fun to see a baby-faced Bono dancing around a Dublin stage, what many music fans are really after is a chance to see the three interact and perform, which doesn't happen until the end. In fact, when they finally jam to The Band's "The Weight," credits are rolling. There is magic though, in Page's satisfied smile listening to a Link Wray recording and The Edge and White's boyish delight when Page begins "Whole Lotta Love."