Music critics are asked endlessly to explain the star system at the top of a review. Is it for the orchestra? For the interpretation? The soloist? The conductor? Is it for the magic (or otherwise, of course) of the moment?

The reasons behind an allocation are often an amalgam of instinct, experience and hard evidence. However, the four-star award for the SCO's closing concert of the season on Friday night is to the musicians for their utterly enthralling playing of Beethoven's Eroica Symphony, which preceded a stirring and dramatic account of Haydn's Nelson Mass.

The scheduled conductor for the night was Olari Elts, principal guest conductor of the SCO. He was taken ill and replaced at short notice by the relatively little-known German, Andreas Spering. And therein lay the backstage drama of the night.

Spering, strongly associated with historically informed performance, divided opinion in the SCO. One view asserted that the quality of the performance had "nothing to do with the conductor"; another held that, though he might be "technically under-developed", his vision is sound.

Personally, I cannot accept that the supremely revelatory account of the Eroica, which unfolded with compelling intensity, had no connection with Spering.

Where Sir Charles Mackerras, in his famous SCO performance and recording of the symphony, deliberately brought out what he called "the barbarity of Beethoven", Spering's vision was at another pole: refined, sophisticated, endlessly expressive, and - quite shockingly for such a revolutionary work - almost intimate in parts.

The texturing of SCO playing was light, transparent and with a real lilt where there is commonly aggressive drive. All the drama was there, sure, but this was also Beethoven at his most radiantly lyrical, and, as every page and each unhurried movement progressed to the next, the experience became more magnetic. The playing was out of this world.

The thrill in the Haydn mass, crisply directed by Spering, came partly from the fact that it was played in its original version, without woodwind and horns, partly from the vivid, gleaming and articulate singing of the SCO Chorus, and partly from the well-matched quartet of soloists, with Elizabeth Watts's brilliant soprano voice, the gloriously creamy and rich mezzo of Karen Cargill, James Gilchrist's unshakable tenor, and the mellow maturity of Christopher Purves's warm bass baritone blending wonderfully in a well-focused account of the great Mass.