Crossover is a hard row to hoe sometimes-so hard, in fact, you wonder why people even try. The ground that's tilled rarely, if ever, gives up a good crop in return. So if soprano Renee Fleming wants to drop her voice a couple octaves and cover Arcade Fire, Band of Horses-and, naturally, "Hallelujah"-no one can stop her, but it's not like folks on either side of the indie-classical chasm are gonna hold their hyper-critical, specialist fire. (I'd say Fleming's take on "Intervention" is strong. Ditto the Band of Horses number. The rest: stay away.) And, as the Times has noted, there's not much combining of disciplines on [...]