I treated myself to prog and jazz/rock fusion pioneers Soft Machine at the TLA Sunday night. It was the second stop of the British band's first U.S. tour in 43 years. My admiration for them is deep-rooted; I purchased "Soft Machine 4" back in the mid-70s and rediscovered the group several years later when my college roommate randomly put "4" on the dorm room turntable, leading to a semester-long exploration of the Canterbury-bred group. None of the original members were present Sunday, but lightning-quick and remarkably inventive guitarist John Etheridge joined in '75, drummer John Marshall came onboard in '72 (capably filling the huge void left by cofounder Robert Wyatt) and bassist Roy Babbington dates back to the aforementioned "Soft Machine 4" (1971). Add Theo Travis (woodwinds, keyboards) and the quartet delivers impassioned prog classics "Hazard Profile Part 1" and "Gesolreut" and bridges old to new with its updated version of "The Man Who Waved at Trains," originally from the 1975 album "Bundles" but reimagined on the freshly minted "Hidden Details" album. Soft Machine effectively intertwines high-energy numbers with the pastoral. Theo's rapid-fire sax play on "Peff" and Etheridge's frenetic guitar runs on "Tale of Taliesin" playfully volley with the ethereal "Kings and Queens" (1971) and 2018's "14-Hour Dream." Soft Machine, as one audience member quipped, "may look like a bunch of old guys but they certainly play as if they have eternal youth" -- and play they did for a searing hour and 45 minutes on this damp autumn night on South Street.