Colin Stetson is a band all his own. With such extended techniques as circular breathing, overblowing and percussive key-tapping, his bass saxophone creates a deep world of sound — no electronics needed, thank you very much. At All Tomorrow's Parties, Stetson opened Saturday's Portishead-curated Paramount Theatre bill all by his lonesome. But if you'd closed your eyes, you wouldn't have known he was alone from the swarming textures that filled the room. In addition to a deep performance of "Judges" from this year's stunning New History Warfare, Vol. 2: Judges, Stetson also previewed a new piece he's temporarily referring to as "The Twins."