Built around the masterful songwriting and commanding vocals of bandleader Dave Heumann, Arbouretum spent the 2000s and 2010s slowly trickling out excellent albums of slightly cosmic folk-rock. As time went on, the band leaned into a British folk influence, lacing Heumann's narrative songs with haunting traditionally informed melodies. Ninth album Let It All In finds the band at the clearest articulation of their sound ever, blurring the boundary lines between woodsy folk, rural psychedelia, and an experimental take on roots rock. "No Sanctuary Blues" finds Arbouretum at the crossroads of all of their varied impulses. Solid rhythm section playing shifts between bar room rock and sprawling drone while Heumann steps away from delivering spirited vocals only to offer Richard Thompson-grade guitar soloing. The moments of cosmic space-out are highlighted by keyboardist Matthew Pierce's unobtrusive synth textures. The following instrumental track "Night Theme" also showcases Pierce's synth playing, contrasting mellow folk-rock riffing with detuned alien keyboard tones. The barreling Krautrock beat that drives the title track leaves plenty of space for Heumann's guitar tangents and lyrics exploring the differences between mass consciousness and an internal world. The song pushes forward for nearly 12 minutes, engaging and tense for the entire time. It's a boiling point for an album made up of various understated moods. Much of Let It All In tends towards introverted performances, from the metered melancholy of "Headwaters II" to the drifting, sleepy honky tonk airs of closer "High Water Song." Mellow songs like these, both steeped in a Grateful Dead influence, offer soft counterpoint to the album's more fiery performances. Excellent musicianship, deft production, and Heumann's lyrical ponderance of both universal and personal themes all make for a listening experience as offhand as it is captivating. Arbouretum comes on as gentle as a rolling creek, never letting on the full range of their powers until the songs have silently grown from still waters to cresting waves.