If gobbling up McNugget-size chunks of institutionalized indie rock at the annual CMJ Music Marathon is unappetizing to your anticonformist tastes, then the Neon Marshmallow Festival makes for the perfect—and perfectly noisy—counterprogramming. The Chicago-spawned free-for-all of outer-limit sounds is planting its flag in Williamsburg for a three-night blowout, mounting a wildly impressive array of real new-music pioneers, ambient specialists and electronic pathbreakers. Can’t-miss acts include second-wave minimalist superhero Rhys Chatham and his downtown brother-in-arms, microtonal maestro Phill Niblock. Liz Harris, the one-woman show who performs as Grouper, brings guitar, keys and effects to conjure ever-more hypnotic and transcendental oceans of sound. And gui-terrorists Kevin Drumm, Alan Licht and Loren Connors and synth wizard Carlos Giffoni will offer updates on their long-running excursions into the outer reaches of the harmonic spectrum.