Would Mozart use a mobile phone?; MUSIC

Does it matter whether Mozart operas play in powdered wigs or polo necks? Are classic arias compromised by being sung into a mobile phone? These are persistent questions nowadays, and they'll have figured in the mind of anyone who caught the new English Touring Opera Marriage of Figaro which opened last week in Cambridge, or the revival of Cosi fan tutte at Covent Garden: productions which come from different sides of the tracks, socially and financially, but talk the same language, albeit in different accents.

ETO's is rougher but invigorating. The production updates everything to a time around the present and a country-house menage more Iris Murdoch than Beaumarchais. The Count becomes an aristocratic photographer surrounded by close personal customers of Vivienne West- wood, and living in a modernist mansion with enlargements of his supermodels past and present on the walls. One of them, now sadly past, is the Countess, who has chocolates and videos of Kiri te Kanawa singing "Porgi amor" for consolation.

You could ask why Figaro has to be like this. It doesn't. Nor does this update quite satisfy the feudal plot requirements. By what prerogative can a 20th-century fashion photographer send Cherubino off to war, or claim a legal (as opposed to circumstantial) right to bed his servants?

But Stephen Medcalf's production is not the gratuitous romp it's been dismissed as. This is a considered piece of work, alive with good ideas that may stray into vulgarity but still make a point - which is that the folie journee of Figaro is one great flirt with image and reality. Children become lovers, boys become girls, servants are masters, and masters are confounded. Almaviva's camera lens, with its potential for recording truth or perpetrating fiction, has a place here. And so does the abundance of 20th-century lifestyle gags that Medcalf packs into the show, from mobile phones to exercise machines. There are so many you begin to tick them off, waiting for the Internet joke that's bound to surface next. But the cultural disorientation that results from forcing Mozart to cohabit with a phone-fax can be purposeful if it shocks the audience into alertness and, maybe, a new response to a known situation. As often as not, that's exactly what happens here in a production which is well-acted and certainly funnier than most. Perhaps it's my prepubescent sense of humour, but I liked the idea of a Countess with a personal aerobics instructor (Don Basilio), who takes Prozac for depression rather than smelling-salts for the vapours. I also liked the way Medcalf turns the Countess's Act II inner cabinet into an ensuite bathroom, giving Susana (for once) a plausible reason for being in there so long and not hearing the Count bang on the door. She was, of course, in the shower!

Anna-Clare Monk's Susana is a tough cookie, but a lovely voice that sparkles with clarity and spirit. Matthew Hargreaves's Figaro is mild-mannered, never quite squaring up to his employer, but nicely sung. And the rest of the cast give capable support, with decent playing from the ETO orchestra under Andrew Greenwood. My only caveat is that Act IV plays on the same indoor set as everything else, and the attempt to turn it into a photographer's studio "garden" only confuses what should be the great sorting out of relationships at the end. But otherwise this is a good show: clever, riotous fun.

There are no riots in the Covent Garden Cosi, whose muted designs and unhysterical, immaculately underplayed dramatic values make it as discreet and elegant a piece of work as Figaro is bold and brazen. But the milieu of the production is the same: a world of stylish, 1990s idle rich with haute couture on their backs, mobile phones in their pockets and time on their hands. Jonathan Miller has revived his own staging with a new, young cast. Their performances are exceptional, alive with subtle detail and a flesh-and-blood humanity that truly liberates the piece from the remove of history - especially at the moment in the double courtship where the conversation dies and Mozart steps out of his period to speak for tongue-tied lovers everywhere. I always like that moment, but I've never felt it register so poignantly.

Rainer Trost, Bo Skovhus, Soile Isokoski and Helene Schneiderman are a delectably "natural" quartet of lovers: better vocally in the ensembles than the solos, although Schniederman is pure perfection in her Act II aria. Dietfried Bernet conducts for lightness, without much character; but he could have picked up some tips on that subject from his audience. The second night formed part of Paul Hamlyn Week, when the entire house is bought by a charity and the tickets issued to people who are disabled, disadvantaged or otherwise unlikely ever to get to Covent Garden. Temporarily, the house becomes egalitarian, and it lifts the heart: especially to see the stalls de-colonised of bankers.

The Royal Philharmonic Orchestra's new music director, Daniele Gatti, is a proven force in opera, with good work at Covent Garden behind him and another new appointment, running Bologna's Teatro Comunale, in front. But taking on a concert orchestra, especially one with the problems of the RPO, is a different ball-game. Whenever I've talked to Gatti I've been enormously impressed by his artistic vision and integrity: his plans for repertory aren't radical, but they're thought-through, intelligent, and on paper he sure as hell looks like the man for the job. But on the platform it's taking time for him to make his mark. Last weekend's Barbican concert was uneven, with a strong, sometimes visionary Tod und Verklarung of Strauss but a dismal Ravel G Major Piano Concerto, partly down to an under-form Alicia de Larrocha but equally to thin, spiritless playing from the orchestra. Gatti seemed to make all the right moves, but they weren't getting results. A failure of communication.

It was a happier story two nights later when Michael Tilson Thomas and the LSO occupied the same stage for the second instalment of their Debussy series. The repertoire here was off-mainstream: the obliquely suggestive ballet Jeux, and the incidental music for that perfumed, fin de siecle religio-erotic drama Le Martyre de Saint Sebastien. Neither score communicates particularly easily, but they seem to run in Tilson Thomas's blood and worked superbly here, with a wonderful sense of the old relationship between MTT and his former orchestra re-establishing itself.

The event of the week, though, was Evgeny Kissin's astonishing Chopin and Schumann recital at the Festival Hall on Wednesday. The last time I wrote about Kissin I called his genius demonic and got an avalanche of outraged mail as a result. But whether they be from God or the devil, this astounding 25-year-old has gifts that beggar comprehension. His phenomenal technique, exemplary musicianship and very presence at the keyboard are electrifying. Casting caution to the wind, I'd say he's probably the most exciting pianist of our time: not beautiful to watch - the arms wheel angularly like the pistons of an engine, while the fingers curl and stab like steel-clad spiders on the keys - but totally compelling. He's clearly incapable of shaping a dull phrase, and from the repeated E-flats and G-flats of the last Chopin Ballade he can't seem to play a dull note either. Some failing.

'Figaro': Brighton Theatre Royal (01273 328488), Tues & Thurs; then touring. 'Cosi': ROH, WC2 (0171 304 4000), continues Mon & Tues, to 19 Mar.