Album: Robert Plant and Alison Krauss

Raising Sand (Decca/Rounder)

More often than not, the Great Band Reunion is a sure sign of creative stagnation, a desperate attempt to claw back the last vestiges of credibility by worn-out musos in career free-fall. That couldn't really be said of Robert Plant, who has exhibited a healthy interest in new sounds, from folk to prog to desert blues, in his recent solo outings; but even allowing for his restless creativity, it's hard to convey the all-round excellence of Raising Sand. Never mind the Zep reunion – Plant should should think hard about extending this collaboration.

The seed of this project had its initial germination a few years later when the pair first sang together at a Rock'*'Roll Hall of Fame tribute to Leadbelly. Their voices have the kind of perfect harmonic and timbral congruence that occurs very rarely in any genre, with Plant reining in his naturally demonstrative flamboyance to fit snugly with Krauss's pure, high tones. The effect, on a song like "Stick With Me Baby", is an extraordinary intimacy, Plant's hushed entreaties allowing her lustrous harmonies to burnish the lines to a sort of sonic satin-gloss finish. Graceful and elegant, it's a blend comparable to that created by Gillian Welch and David Rawlings, or even – whisper it quietly – the heart-rending duets of Gram Parsons and Emmylou Harris.

Crucial was the choice for producer of T-Bone Burnett. He has furnished the duo with simple yet sumptous settings that impose compelling atmospheres while affording the voices ample space. Equally crucial was the choice of material, mostly classy but little-known songs from composers as diverse as Little Milton, Doc Watson, Townes Van Zandt, and Tom Waits and Kathleen Brennan, nearly all receiving treatments that somehow manage to be both definitive and transformative – not least in the case of the Page/Plant number "Please Read The Letter".

The same can be said for two Gene Clark compositions, "Polly Come Home" and "Through The Morning, Through The Night", which have acquired a deeper, more haunting beauty courtesy of Plant and Krauss's respective solo leads, and for Waits and Brennan's "Trampled Rose".

Sweet and stealthy performances of obscure songs like "Rich Woman", "Killing the Blues" and "Sister Rosetta Goes Before Us" inescapably bring to mind the haunted sadness of Gram Parsons's Grievous Angel. There is no higher praise.

Download this: 'Killing the Blues', 'Gone, Gone, Gone', 'Polly Come Home', 'Please Read the Letter', 'Trampled Rose', 'Stick With Me Baby'