It's not uncommon for one song to completely turn around the fortunes of a band or artist. It could be a new group's first demo, overheard by someone who knows someone, then picked up to soundtrack a car advert or a key scene in a film. Or it could be a track buried deep in the back half of the fourth album by a struggling singer who knows their label won't accept three-star reviews as a substitute for record sales much longer. Either way, all it takes is a single solid-gold melody to set a career rolling down a completely different, unexpected path.

In Sharon Van Etten's case, that song was 'Love More', a tune recorded in the winter of 2009 as the first in an inspired series sponsored by the non-profit organisation Weathervane. Just weeks after its low-key release, the track was covered live at Cincinnati's MusicNow festival by Bon Iver frontman Justin Vernon and The National's Aaron Dessner and suddenly the ears of the alternative music community pricked up: here was a bewitching, unearthed diamond of a song with a ready-made seal of approval, and - better still - it wasn't the work of some obscure figure from a bygone era, but of an active contemporary artist.

For Van Etten, the ball set rolling by that random act of patronage has been gaining momentum ever since. With a bit of buzz behind her, second album Epic - the follow up to the stark, stunning Because I Was In Love - snuck onto a few 'Best of 2010' lists, prompting Jagjaguwar to offer her a home alongside Vernon at the label. In the past two years she's played to bigger crowds, both at home and abroad, than ever before, and recently shone in front of an audience of millions on Jimmy Fallon’s Late Night show. Her newly raised profile has also helped secure a rather impressive list of collaborators for her latest full-length. Produced by Dessner in his garage studio with a band including Walkmen drummer Matt Barrick and Doveman’s Thomas Bartlett, and vocal contributions from Julianna Barwick, Wye Oak’s Jenn Wasner and Beirut frontman Zach Condon, Tramp sees Van Etten bulking up her sound without sacrificing the understated intimacy of previous efforts.

It's not hard to see why all these maudlin indie types have thrown themselves at Van Etten's feet. The Jersey girl specialises in the kind of scuffed, guitar-wielding torch-singer sound that has long served the likes of Cat Power and Feist well, and here she dominates proceedings like a seasoned pro. Indeed, while the album’s personnel list is lengthy, her guests mostly keep a respectful distance, providing the same kind of unobtrusive accompaniment as the 'all-star' bands you’d expect to find backing a veteran. Sure, if you pay attention, you can make out Dessner's fingerprints all over the record - it's there in the ever-present background guitar squall, and especially on rattling lead single 'Serpents' which, appropriately, sounds like a female-fronted National track. Meanwhile, there’s no mistaking Condon’s vocal presence on 'Magic Chords' and 'We Are Fine'.

Gently bombastic album highlight 'Leonard', with its breezy accordion and soaring, uplifting melody is distinctly Beirut-esque, while the pulsing shimmer of 'I'm Wrong' suggests Van Etten has been taking tips on luminescence from Barwick. As lovely as songs like 'Kevin's', 'In Line' and 'Give Out' are, they share with much of the record a melancholy air and funereal pace that can tend towards the overbearing. When the sombre tone is broken, as on 'Ask' or the triumphant 'All I Can' - an ambitious hybrid of Coldplay's 'Yellow' and ABBA's 'The Winner Takes It All' - the results are glorious. But tempting though it is to attribute Tramp’s success to its supporting cast, there is nothing here that wasn’t hinted at on its predecessors. The blend of soul and rootsy grit may not be startlingly original, but here, at least, it’s Van Etten’s and nobody else's that truly shines.