Screeching feedback and lysergic scuzz rock were the greatest selling points for the Flat Can Co.’s 2006 debut.

Since then the quartet has evolved into a ferocious ensemble capable of heady improvisational jamming. Single Live Gonzo! documents a band conducting sweaty groove research à la the Baby Grandmothers and the Who circa 1970’s Live at Leeds.

On the 18-minute “Hydroponic Hand,” the foursome slashes, chokes, and convulses like a single entity. It’s obvious that guitarists Miss Melvis and Keith Pickering, bassist Jimmy D, and drummer Scott Pickering have cultivated a psychic-jazzbo link in the last 12 months.

Most modern noisemakers equate improv with one-off collaborations. But that’s misguided. The spontaneous exploration of sound is no different from an Arctic expedition: Success requires musicians who stick together through the shit — not bolt after the first night of camping. This is something the Flat Can Co. understands.