The records in Casino’s Instrumental Mixtape series (currently on volume 4) are the craftiest of minimalist exercises: some of the tracks are instrumental versions of previously released rap songs, while others are new, but all sound like whooshing abstractions, barely coherent as music, before soothing melodies and harmonic structures reliably surface. When he started releasing his beats on their own, stripped of vocals, he stood revealed as an avant-electronic experimentalist, and a certain friendly weirdness became apparent what sounded murky behind a rapper ’ clicked when presented as a standalone environment with room to breathe.