José González & the Gothenburg String Theory, Barbican, London

José González is all too often done a disservice: his magnificent cover of The Knife's "Heartbeats" launched him into the collective consciousness, and his wondrous versions of songs from Massive Attack to Bruce Springsteen have since captured the ears of many a casual listener. What's usually overlooked is the musical brilliance of the man himself, but tonight, playing with "maverick orchestra" the Gothenburg String Theory, it's never in doubt.

The orchestra, often the hallmark of overproduced, saccharine pseudo-pop ballads, is a dangerous weapon in the musical arsenal. When incorporated well, though, as it is tonight, it can be tremendous.

The Argentinian-Swedish folk songwriter and the GST have managed to conjure a truly wonderful relationship. González's fragile vocals are counterbalanced by his agile fingers, making his solo renditions of the pleading "Fold" and absorbing "Hints" utterly beguiling. But it's when the GST emerge that the show takes on another dimension.

Led by dynamic conductor Nackt, the intrepid orchestra embrace the unorthodox – using plastic bags for percussion in "Far Away" – the contemporary and the traditional, combining electronic background noises with luscious string arrangements and insistent brass. They provide scope on "The Nest", and match the vocal ebbs and swells of "Crosses" like musical shadows. The performance of Kylie Minogue's "Hand on Your Heart" is breathtaking, González's tremulous vocals and GST's rich orchestral texture uniting to heartfelt effect.

The audience is rapt throughout, whether clapping their hands to the triumphant climax of "Down the Line" or marvelling at the tear-inducing wonder of "Heartbeats". Mixing spectral beauty with gifted musicianship, this is a special partnership which isn't just impressive, it's progressive.