In a guitar-drums duo, you rarely expect the rhythm to earn lead billing. But Charles Rumback is a worthy exception: The percussionist, a veteran of the Chicago free-jazz scene, can make a drum set sing— exploring melody and timbre within his gleeful grooves, treating each ride cymbal and brushed snare like its own voice in a choir. On his second collaborative LP with guitarist Ryley Walker, recorded during sporadic sessions in 2017 and 2018, the kit often functions as the lead instrument: His tom-toms form a distinct tonal center within the ambient haze of “If You’re Around and Down,” the descending, three-tom pattern essentially functioning as a riff within Walker’s evaporating electric mists; on the free-fusion New Age hymnal “Menebhi,” his funky open snare, chaotic rim clicks and bombastic tom rolls are almost danceable within Walker’s calming underwater landscape, aided by a snapping programmed beat. The guitarist—one of the most unique players in modern folk and psychedelia—complements these rhythmic excursions in a quiet dialogue, content to color with echo, delay and fingerpicking. The centerpiece is “Idiot Parade”: Rumback maps out scintillating cymbals and muted toms, and Walker probes at the groove with acoustic flourishes, supplemented by Nick Macri’s growling, bowed bass. The most memorable moments on Little Common Twist are simultaneously tranquil and exciting, like staring at a blue sky full of slow-rolling cumulus clouds that morph into strange formations.