A CYCLE of the Shostakovich symphonies is no small matter. There are 15, most of them emotionally battering. And played with other, time- related Shostakovich scores in the way the LSO is doing at the Barbican, they make a series so extended that the orchestra has decided to divide it in two: taking a break after tonight and starting up again in mid-October.

For anyone other than a compulsive collector of cycles, the selling point of this series is Mstislav Rostropovich who, as a pupil and champion, enjoyed as close a relationship with the composer as anyone alive today. That gives his readings a peculiar authority; and the substantial programme- book makes much of it, with photos of the two men from the 1950s and 1960s, sharing confidences, rarely looking happy. Not that there'd have been much reason to look happy then, but it was certainly expected, and especially from artists. Soviet art was press-ganged into meaning, and its meaning was to celebrate. Abstraction - anything that seemed to prioritise form over content - was indictable. And the majority of Shostakovich's symphonies accordingly issued with some obliging Socialist-Realist programme that in 1976 earned him a state funeral, and the reputation of a good, loyal Soviet as he lay fresh in his grave.

But music doesn't submit to meaning so easily. In 1979 the Russian journalist Solomon Volkov published Testimony, a supposedly verbatim account of conversations with Shostakovich, which claimed that these symphonies celebrate nothing, except the courage of an individual spirit to defy the state machine. What we had learnt to hear as affirmatory, rejoicing music was in fact ironic. Anyone who didn't register the irony, said Testimony's Shostakovich, was a "fool".

Since then, the authenticity of Testimony has been open to debate. Its detail looks like fabrication, but its general accuracy tends to be acknowledged - except, it seems, by the author of the LSO's programme notes, a Russian who, bizarrely, has been allowed to rehearse the old party line as though Testimony had never existed.

The litmus test of modern Shostakovich readings is the last movement of the 5th Symphony, which played last Sunday at the Barbican. I was amazed to find the programme-note describe it as "a life-affirming finale", related to "the idea of culture triumphing over barbarism and the immortality of beauty". This is what you would have found in the notes for a performance in Leningrad in 1960. And it was not the view taken by Rostropovich last Sunday, in a reading that was pugilistic, dark and driven.

Driven darkness has, in fact, been the general tone of the symphony series to date (we've now reached No 7), accentuated by playing the symphonies alongside lighter scores - the Jazz Suite, music from the film New Babylon - that show what Shostakovich sounds like when he's genuinely upbeat. And I have to say that I've found it all a touch heavy-handed, with sledge- hammer rhythms, stodgy textures, and a grim determination in the playing which suggested that the orchestra wasn't exactly enjoying the experience.

Rostropovich is of course a great musician, and a galvanising presence on the platform. Nobody could doubt his vision of these scores, his depth of understanding. But communicating that vision is another matter. His technique as a conductor is a mess: control surrenders to emotion. And the result, in the game of masks which the Shostakovich symphonies seem to play, is that the inner life of the music doesn't always show through the outer rhetoric. Symphony No 3 for example - admittedly no jewel in the composer's crown - was dull. No 4 was superb in parts, empty in others. No 5 was outstanding, and No 6 patchy.

In fairness I should add that there's been exemplary playing throughout from the LSO, whose stature as the finest orchestra in Britain remains unassailable. But as Rossini said of Wagner, this series has so far been a thing of sublime moments and uncomfortable quarter-hours. In other words, modified rapture. And very dodgy programme notes.

London is suffering (if that's the right word) a surfeit of concert opera. There were two on Tuesday - Weber's Freischutz at the Barbican, Bartk's Bluebeard's Castle at the Festival Hall - and in going to Bluebeard I probably made the wrong choice. Part of a Philharmonia/Dohnanyi series that perversely couples Haydn and Bartk (contrasting aspects of the Austro-Hungarian tradition, with the emphasis on contrast), it was rigorous, intelligent and well-played, with decent soloists in Laszlo Polgar and Kornelia Kallisch. But it lacked dimension, richness, atmosphere; that was partly down to the old problem of the stone-dead Festival Hall acoustic but it was also down to unimaginative use of the performing space. Some small gesture of theatre would have made all the difference.

Lucio Silla, one of those marvels of Mozartian juvenilia, is on tour through Britain in a very superior student production: the first effort of the new Manchester-based European Opera Centre which has been set up to nurse exceptional young singers at the brink of their professional careers. A similar project is about to launch in Baden-Baden, and it can only be a good idea.

But this opening-shot Silla isn't the liveliest advertisement for what's to come. The cast I heard (they alternate) was competent, not special; the musical direction dull. And though I warmed to Brigitte Fassbaender's production - which turned opera seria into opera semi-seria - it took a while. The best thing was the post-modern conceit of Bettina Munzer's designs, which I liked a lot. But they were hardly the point of the exercise.

The most ingenious designs I saw last year were almost certainly the ones by Alison Chitty for the Glyndebourne children's opera Misper; and seeing the show again last week, I was even more entranced than first time round. Glyndebourne does nothing by halves, and though this is a kids' piece, it's for kids with style: a fabulous confection that combines street credibility with theatre magic. I love everything about it: Stephen Plaice's sharp libretto (peppered with reminiscences of his past life as a scriptwriter for The Bill), Keith Benson's virtuoso lighting, and Stephen Langridge's alive direction, which gets amazing performances from a largely amateur, school-age cast - including a chief villain, Mark Enticknap, so compellingly cool it made me feel inadequate. I've also grown to love John Lunn's score, which sounds like big-screen Sondheim with a touch of rap, but has enough invention not to be in total thrall to its assorted models. Memorable and haunting, it's exactly what the circumstances call for. And the pity is that, just as last year, there's no prospect of its playing London. Still, it does its job at Glyndebourne, sweeping in a sudden, drastic change of culture. It's a heartening thing to see the place awash with families in anoraks; a downright joy to hear the bar staff ask not "Moet or Bollinger?" but "Plain or smokey-bacon?". Colin Southgate wouldn't like it. Here's to Glyndebourne where, at last, they do.

The Shostakovich cycle continues in Oct. 'Lucio Silla': Oxford Playhouse (01865 798600), tonight; Llandudno North Wales Theatre (01492 872000),Tues; Edinburgh Festival Theatre (0131 529 6000), Fri & Sat.