The Sons of Champlin - Loosen Up Naturally (1969)

Wikipedia mentions about this group: "The Sons of Champlin are an American rock band, from Marin County in the San Francisco-Bay area, formed in the late 1960s. They are fronted by vocalist/keyboardist/guitarist Bill Champlin, who later joined rock band Chicago, from 1981–2009, placing Sons of Champlin on hiatus from 1981–1996. They brought to the late 60's music scene in the Bay Area a soulful sound built around a horn section, sophisticated arrangements, philosophical themes, Bill Champlin's songwriting and blue-eyed soul singing, and Terry Haggerty's jazz-based guitar. They are one of the 1960s San Francisco bands, along with Jefferson Airplane, The Grateful Dead and Moby Grape". You can find this album on Spotify.