Classical Music: Double Play/ Edward Seckerson and Stephen Johnson compare notes on Berlioz: Harold in Italy; Tristia Monteverdi Choir, Orchestre Revolutionnaire et Romantique / John Eliot Gardiner (Philips 446 676-2)

Byronic Berlioz (or "Travels with my Viola"). It's quite a trip, whichever way you look at it. And any performance that can tweak at your senses so that hearing is not quite believing (meaning that Berlioz's startling choices really do sound startling) is halfway there. As you would expect, Gardiner's Orchestre Revolutionnaire et Romantique - a bit of a mouthful, but as good as their word - prick up your ears. Three bars into the opening fugato (wary cellos and basses on the mountain trail) and the highly "vocal" (no, "operatic") timbre (overripe, engagingly husky) of Gardiner's first bassoon is demanding attention. Berlioz, alias "Childe Harold", broods, and Gerard Causse - who must, in this context, be both violist and poet - muses, solo harp (his lyre) tendering a discreet accompaniment. It's the stuff of dreams, with or without the opiates. And Causse is very much the dreamer: light, limpid tone evaporating to some wonderfully withdrawn pianissimi in the upper register of the instrument.

Those mysterious arpeggiations shrouding the evening hymn of the second movement - "The Pilgrims' March" (an idea of such radiant simplicity, it almost, quite literally, passes you by) - might almost be happening inside your head. Or rather, Berlioz's head. Exactly right. The bucolic drones, jaunty pipings and lazy cor anglais serenade of the third (individually and collectively, the ORR woodwinds shine - and I mean shine) are appropriately rose-tinted. But when the heat is on, Gardiner and his team are wired to rip-roaring effect. Trumpets and cornets lend that characteristically tangy edge to the tutti sound, the timpani crack on home with a will.

No package tour, this. And there's more. In the aftermath of the Brigands' orgy, Gardiner reflects on Tristia - "sad things". Exquisitely sad things. Three quite separate works published as a triptych in 1852. The two choral settings have their own peculiarly fragrant atmosphere, not least La mort d'Ophelie (Ballade) with its keening, strangely distracted ritornello. And after the death of Ophelia, a magnificent Marche funebre - music for the final scene of an imaginary production, never realised, of the play that first brought Shakespeare to Berlioz. To be or not to be, he wrote the music anyway. And I'd shell out the price of the disc for this morsel alone. "Go, bid the soldiers shoot," commands Fortinbras. Only Berlioz could have taken him at his word. A shattering volley of musketry crowns the muffled drum-laden climax. The rest is silence, broken only by a couple of dying phrases, barely that, and one last gasp - a long, sustained "Ah!" from the wordless chorus - blowing like a chill wind over the tragic scene. Unique. ES

Berlioz had some strange ideas in his time, but Harold in Italy is one of the strangest: a symphony (or is it a commentary on Byron's poem?) with a prominent, non- virtuoso solo instrument - and not just any solo instrument, but the viola, butt of jokes since the dawn of orchestral time (Q: "How can you tell when a viola's playing out of tune?" A: "The bow's moving"). But, being Berlioz, he makes it sound utterly natural. The orchestra evokes Italian scenes - a procession of pilgrims with solemn bells, a mountain boy serenades his intended - while the viola stands to one side and watches pensively. Byron's Harold may have been a passionate adventurer; Berlioz makes him a dreamer - always partly detached, even in the final "orgy" scene.

There are no big stylistic surprises in this recording. Most music-lovers will have some idea what period instruments sound like, and none of Gardiner's tempi are extreme. The surprise is in the atmospheric richness: the "Pilgrims' March" is gorgeous, with subtle gradations of colour; the cor anglais solo in the "Serenade" drifts close to the languorous beauty of the song- cycle Nuits d'ete; the bass brass really spit and curse in the finale (yes, modern trombones can be too refined). Then there's another surprise in Tristia - how can this wonderful music be so little known? Granted, the form (three short choral movements) isn't the most practical in modern concert-planning terms, but exceptions could surely have been made, at least for the powerful Hamlet funeral march - almost a miniature tone- poem in itself, with what must be the most devastating use of gunfire in all music.

As a vindication of period instruments in romantic music, I find this superbly recorded disc even more convincing than Gardiner's award-winning Symphonie fantastique (also Philips). Why resist it? SJ