The strings of the 12 Ensemble and the percussion and piano duo of George Barton and Siwan Rhys make natural collaborators, for both regularly explore corners of contemporary music that other groups tend to overlook. Last autumn at Covent Garden they joined forces to provide the pit band for Oliver Leith’s Kurt Cobain opera Last Days, and they have come together again for this touring programme, which was included in the Kings Place Sound Unwrapped series.

Its centrepiece was a new work for strings, piano and percussion by Laurence Osborn, commissioned for the tour, and by quite a margin the most absorbing and worthwhile piece in what was a rather uneven concert. Osborn describes his piece TOMB! as recognising “the necrophiliac side of heritage and our morbid obsession with dead things”. In this case the “dead things” are traditional musical forms like fugue, jig and passacaglia, which flit in and out of the 20-minute movement like apparitions, only occasionally assuming recognisable forms. The effect is intriguing, sometimes unnerving, but always engaging, and full of textures that are never quite as straightforward as they seem.

Two short numbers from Mica Levi’s score for the 2013 film Under the Skin, one doom-laden, the other sweetly sentimental, and Fausto Romitelli’s Flowing Down Too Slow, with its spectralist harmonies and teasing interplay between the strings and a pair of sampling keyboards, made up the rest of the first half of the evening, while the second was given over to Harold Budd and Brian Eno’s Ambient 2: The Plateaux of Mirror. Barton had rescored what began as a series of 10 of Budd’s semi-improvised piano solos, to which Eno had added sonic “environments”, carefully preserving the piano solos but using the strings and percussion to recreate the studio effects of the original. It was a beautifully imaginative reworking, done with great tact and refinement, but sometimes the piano doodles seemed an insufficient centrepiece, despite evocative titles such as An Arc of Doves and Among Fields of Crystal. Eno once said that ambient music “must be as ignorable as it is interesting”, but too much of this was definitely ignorable.

• Repeated at Cheltenham festival on 14 July