I would imagine that having the sort of life where you can call up Trent Reznor just to chat or get Chan Marshall to record backup vocals for your album would be pretty fucking rad. But if El-P derives any joy from it, he’s not letting on. The rapper, producer, and Def Jux honcho has always been one of the tweakiest dudes in the rap underground, which loves charismatic MCs who can convince you they’re mentally unstable, and his new I’ll Sleep When You’re Dead (Definitive Jux) sounds like a straight-up nervous breakdown. The beats are like classic hip-hop run through a suitcase of distortion pedals and an acid bath, and when El-P and his gang of indie-famous guest MCs (Cage, Aesop Rock, Slug, Mr. Lif) tell us how they really feel, it’s usually somewhere north of “totally freaking out, man” but just shy of psychosis. In less capable hands this might take a wrong turn into unintentional comedy, but like Reznor–who contributes production work and vocals to one track here–El-P has the forceful persona and daredevil musical imagination to make his downward spiral a compelling ride. Hangar 18, Yak Ballz, and Slow Suicide Stimulus open. a 10 PM, Abbey Pub, 3420 W. Grace, 773-478-4408 or 866-468-3401, $20, $18 in advance, 18+.