“Critical Mass” captures the fierce, intuitive chemistry between Mars Williams and Vasco Trilla, two improvisers whose shared language turns sound into a volatile, shape‑shifting force. Recorded in Barcelona at the aptly named Thriller Underground Facilities, the album unfolds as a continuous surge of energy where reeds, toy instruments, drums, and percussion collide, separate, and recombine with restless momentum. Williams moves between raw, vocalized tenor eruptions and fragile, breath‑inflected textures, while Trilla constructs a percussive environment that feels both architectural and explosive, using resonance, friction, and pulse to propel the music forward. Across five expansive pieces, the duo navigates zones of density and suspension, letting each gesture mutate into the next without hesitation. “Critical Mass” stands as a vivid document of two artists pushing deeper into their own sonic instincts, creating a music that feels urgent, unpredictable, and alive—an essential entry in the evolving lineage of Not Two’s free‑improvised catalog.