Subgenre-jumping chameleons Boozoo Bajou had already checked reggae, dub, Cajun music, folk, jazz, and pop off their list, but with 4 they go deep into the heart of electronica, as in way deep. This dark and dubby album is almost obsidian as it echoes and drones with the coolest of tempos underneath, as names like Brian Eno, Basic Channel, and Trentemøller come to mind, although all the music is inspired and purposeful and nowhere near the vicinity of mimicry. Key track "Der Kran" is the entirely unique experience of taking a boat ride down a stream that runs into a cave as echoes and urdus offer a subterranean version of exotica, while "Your Weak Fire" is the kind of bottomless dub that the Rhythm & Sound crew specialize in, although the whispered vocals and wet, loose guitar riffs here are identifiably Boozoo. Highlight "Kodiak" is a song among soundscapes and brings a bit of jazz and spy music for a rare moment of levity, but if the album is single-minded and too close to a mood piece for returning fans, that's the price paid for something so thematically sound. Jon Hassell, Wackie's, Porter Ricks, and Burial fans will welcome such a rich collection of bottomless boom and draggy beats, especially when locked up in the house for the winter, but Boozoo newcomers who use this as their entry point will likely feel they've stumbled into the Fleetwood Mac or Zero 7 section of their record store if they explore the discography much further. Even if it's a one-off, 4 is a welcome anomaly from an unclassifiable duo who seem to give up nothing but.