WITH a baritone soloist instead of a mezzo-soprano, a mantle of darkness descends on Das Lied von der Erde. Some conductors, including Sir Charles Mackerras last night, presumably like it that way, at least from time to time, for it brings a different perspective to what has become one of the Mahler's most familiar works, drawing special attention to - indeed making us thankful

for - the gleaming woodwind timbres and high string tone which, in this alternative version, provide the music with its only chinks of light.

Even the tenor part seems to change personality without the contrast of a female voice, but with a conductor as astute - and apparently as imperturbable - as Sir Charles, the things that needed special attention on this occasion received it, and the things that might have gone wrong did not do so. Since neither of the soloists were the ones announced in the Festival brochure, the success of the performance was all the greater.

True, a certain amount of

re-tuning between movements suggested a degree of unease on the part of the Czech Philharmonic. But Simon Keenlyside, replacing Thomas Quasthoff, sustained the closing Abschied as impressively as a baritone can be expected to, rousing faint, perhaps inevitable, memories of Fischer-Dieskau in the upper register, but sounding like nobody but himself in the lower.

Robert Gambill, replacing Roland Wagenfuhrer as tenor, faced the problems of the opening song with initially less equanimity, but it was here that Sir Charles's expertise was particularly useful, as it was indeed throughout the work. Though he could be expected to revel in the sharp detail, the sudden frissons, the finely gauged climaxes of the score, his scrupulously exploring - or

re-exploring - of the work's sonorities was constantly rewarding, not least in

the orchestral contribution to the finale, filled with forlorn bird-song.

In the male-voice version, The Song of the Earth can easily become bogged down. In Janacek's Sinfonietta, at the start of the programme, Sir Charles was on less treacherous ground, and his ebullient, loving performance of it with an orchestra that had the music in its bones, was the ideal obverse of the Mahler.