As the original Soft Machine lost and gained bandmembers and transitioned from psychedelic pop to jazz-rock fusion from the late '60s to the mid-'70s, some of the group's earliest fans -- not to mention a scattering of pop music pundits here and there -- began to assert that SM's heydays had passed. Indeed, by the release of 1976's Softs, no original members were present in the core lineup, leading some to question whether the band should even be called "Soft Machine." Yet the group's transitions in style and membership had been seamless enough that, at least to some listeners, the Soft Machine name could be affixed to the Softs album with nary a raised eyebrow. Flash forward several decades to the 2010s and three of the musicians present on Softs, drummer John Marshall, bassist Roy Babbington, and guitarist John Etheridge -- joined by newcomer saxophonist/flutist/keyboardist Theo Travis -- continued to carry the SM fusion-era torch on a pair of Soft Machine Legacy albums released by the MoonJune label: 2010's Live Adventures and this album, 2013's Burden of Proof, the first studio-recorded outing by this particular quartet. Babbington, Marshall, Etheridge, and Travis already proved themselves to be a highly capable quartet on Live Adventures, and Burden of Proof is further evidence of their individual skills and collective unity of purpose.
The SM "Legacy" surfaces in a spacy version of the late Hugh Hopper's "Kings and Queens" (from Soft Machine's Fourth) with Travis on flute, and also in Travis' delay-echoed Fender Rhodes introduction to the leadoff title track, not to mention the tune's intersection of Babbington's streamlined modal walking bass with the sax-guitar unison melody line, as Marshall swings and rolls loosely through the tune's angularity. Elsewhere, several short bridging tracks provide atmosphere, and the group also ventures into lengthier group improvisations, sometimes searching, sometimes tumultuous, as on "Voyage Beyond Seven," "Green Cubes," and "Fallout," the latter bookended by a theme hinting at a fragmented "21st Century Schizoid Man," although far more relaxed. Again touching on '70s Soft Machine, Travis brings arpeggiated Rhodes to the intro and chorus of album highlight "Black and Crimson" -- also a showcase for Etheridge's wide vibrato-laden phrasing -- then pushes his tenor sax to the limit on the slam-bang sax-drums duo "The Brief," which also proves that Marshall can still be a percussive dynamo. But despite its jazzy interludes and heated interplay between Etheridge and Travis, "Pump Room" has a heavy boogie-rock beat, and the roadhouse jazz-blues-flavored "Pie Chart," with Travis wailing away R&B style, is about as far from the Soft Machine oeuvre as you could get. The bandmembers seem to be enjoying themselves here, and out to prove nothing except how to have a good time. The "Soft Machine" thread arguably comes close to breaking on "Pie Chart," but elsewhere the connection remains strong -- strong enough that when this quartet dropped the "Legacy" portion of its name prior to the release of 2018's Hidden Details, observers responded with...nary a raised eyebrow.