Aphex Twin’s headlining DJ set at Barcelona’s Sónar festival last weekend was a nonstop onslaught of sensory overload: breakneck tempos, strafing lasers, overdriven bass, and earsplitting dissonance more in line with a noise show. But “Blackbox Life Recorder 21f,” the Cornish musician’s first new music in five years, is an altogether friendlier affair. Much like “T69 Collapse,” which opened 2018’s Collapse EP, the new song brandishes its analog-sounding drum machine as though it were a shiny new toy, snares and rimshots so dry they’re practically vacuum-sealed. He offsets the skipping drum groove with one of the gentlest synth melodies he’s crafted in ages, answering sighing pads with a sweetly downcast counterpoint. This is Aphex, of course, so nothing is as it seems at first. The groove thickens as it goes: Nagging breakbeats poke and prod, while insistent crash cymbals blanket the high end in white noise. But he never lets it get too extreme; every time you think things might go off the rails, he falls back on those soft, ruminative synths, closing with nearly a minute of somber ambience. It’s an unusually reflective look for electronic music’s biggest trickster.