Acts usually go weird after achieving a level of success with more conventional -sounding releases. Some of the leading lights of the ongoing great American guitar hero - in the explorative sense of John Fahey and Jerry Garcia rather than the fretboard fireworks, say, Jimi Hendrix - revival have chosen to go the other way.
As with fellow fretboard traveller Ryley Walker, Steve Gunn's roots are in free-range improvisation. Also similarly to the Illinois-born Tim Buckley and John Martyn enthusiast, Gunn continues to dabble in more esoteric side projects, such as a recent banjo-wielding spook-folk collaboration Seasonal Hire with the Black Twig Pickers, even as his songwriting prowess is blooming.
As such, the relatively conventional, lean and street-smart folk 'n' rock 'n' roll sound of Gunn's third outing as a singer and songwriter as well as a guitarist may come as a surprise. If 2013's sparse, acoustically orientated Time Off still sported mud-flecked overalls with muck on its boots and 2014's mesmerising Way Out Weather balanced between the weed-sprouting pavement and a heat-hazed dusty dirt road, Eyes On The Lines is almost totally an urban beast, with the likes of the urgently throbbing "The Drop" more fit for soundtracking dashes down rush hour streets than field-side rambles and bucolic reveries.
It's also more uniform in tone, tunes and themes than its winningly diverse predecessor. This is both a relative strength and a minor shortcoming. You may well think back with longing to how Way Out Weather found a natural home for both the swirling acoustic tapestry of "Wildwood" and the high-voltage voodoo hypnosis of "Tommy's Congo" as tracks settle into similar grooves and instrumentation remains stuck in a single groove. At the same time, it's hard to resist the increasingly inspired and intense playing of Gunn's combo, who seem to be channelling their mighty recent live form unfiltered in the studio; there's some real telepathy evident throughout these cuts. Just see how, for example, the circular, ringing riffs of "Full Moon Tide" gains momentum like a powerful propeller picking up speed or, at the opposite end of adrenaline stakes, the languid closer "Ark" winds down unhurriedly like a particularly drawn-out sunset.
Then there are the songs, themed loosely around the allure of getting consciously and deliberately lost just to stay on the go, which in a way offers the exact opposite of a newly active touring musician's clichéd bemoaning of the rootless life 'on the road'. It's hard to imagine that the writer of a tune as engaging and alluring as "Conditions Wild" - similar classic rock tricks to Way Out Weather's "Millie's Garden", but with an even more advanced take on melody-craft - spent years steering well clear of songwriting and playing second fiddle - or first guitar - for fellow Philadelphian Kurt Vile.
Above all, however, this a guitar record with a capital G, although you'll look long and in vain for what might pass off as a traditional, guitar face-pulling face-melter. Instead, the humble, common good-serving guitar heroics - a deft riff here, a light flurry of notes there, constantly shifting yet never needlessly busy - are built into the very fabric of tunes such as "Ancient Jules", making it impossible to fully establish where the song ends and the guitar showcase begins, and installing the proceedings with a beguiling whiff of in-the-moment improvisation.
Making experimental music is certainly a noble calling. Sneaking the adventurous spirit of improvisation into a relatively conventional song-based record such as Eyes On The Lines, however: that's truly radical.