OPERA / Tall, dark and Hampson: Thomas Hampson is the thinking man's baritone, equally at ease in everything from Mahler to American musicals. But, asks Edward Seckerson, isn't he just a bit too good to be true?

When they start genetically engineering singers, the romantic baritone will be cloned from Thomas Hampson. As operatic heroes go, this one was made to measure: a gentle giant of a Marcello, a dashing, streetwise Figaro, a swaggering Don Giovanni, a debonair Count Danilow. And if Hollywood were still making musicals like they used to, then Howard Keel would be looking over his shoulder to see how many brides Hampson could hitch under one arm. Central Casting should be so lucky. And the voice: a healthy, pliant, wide-ranging baritone with the uplift of a tenor - all friendly persuasion and disarming ease.

So where's the catch? Nature would even seem to have spared him the 'operatic' ego. The old adage that you ask a singer a question and they give you their resume definitely doesn't apply here. Hampson would sooner talk about his research than his resume. In January he was voted Male Singer of the Year in the International Classical Music Awards, but I expect he's already asking what that actually means. He'll tell you that he's gratified when people are essentially not aware of him as a performer - and he expects you to believe him. 'You see, I don't consider myself a creative artist - my role is as re- creator. I just wonder whether we aren't always talking too much about the performance rather than what's being performed . . . Even the term 'music-making' is sort of objectionable, if you think about it . . .'

Too good to be true? Well, there are those who don't buy it. He can afford the modesty, they say. Perhaps. But an hour or two in his company and you don't have to be a psychoanalyst to know what really drives him. And it isn't ambition. Hampson is an obsessive explorer, collector, purveyor of repertoire (you only have to glance at his discography - from rare Schubert, Rossini and Meyerbeer, neglected Delius and Ambroise Thomas to Stephen Foster, Cole Porter and Irving Berlin).

And it isn't enough merely to discover: he wants to know why, wherefore, context, subtext. If he wasn't a musician, he'd probably be a historian; if he wasn't a performer, he'd almost certainly be a musicologist. He likes to document his own records. A recent EMI disc of 'Romantic Song' by Berlioz, Wagner and Liszt comes with a booklet so hefty you'll have problems getting it back in the CD case.

It's the psychology of history that fascinates him - the reasons things happened. 'We tend to look at historical events so clinically, especially today when information is so readily available. But things happen, have always happened, because people breathe, and eat, and think. I want to know what Housman had for breakfast the morning he wrote 'A Shropshire Lad'. I want to get beyond stereotypes. In music right now we're tending to suffocate in style. Style is not something you can paste on to a performance; it's something you arrive at through understanding.'

So no quick fixes. When Hampson embarked upon his exploration of the great German folk anthology Des Knaben Wunderhorn ('The Youth's Magic Horn'), he arrived at the famous Mahler settings by way of many others. He then initiated a critical edition of Mahler's original piano versions, and took those into the studio. The resultant disc revealed levels of intimacy, of confidentiality, which one would not have thought possible from knowing only the familiar orchestral versions. We began to see what really lay behind the magic casements of these songs. Hampson found colours and inflections he didn't know he had. Style through understanding.

Right now he's up to his elbows in the musical life-blood of his countrymen - American song. And, as ever, his explorations began with the poets and their poems. All roads led to Walt Whitman. He's spent two years researching a new album of Whitman settings for EMI. When word got out that he was 'on the rampage again', the songs came pouring in - a veritable Niagara of them. He unearthed some 220 in six different languages. Among his favourites is Leonard Bernstein's setting of 'To What You Said'. But he won't be singing it in tonight's performance of Bernstein's Songfest - part of the Motorola Festival of American Music, director Leonard Slatkin. In this context, it's the bass and not the baritone who gets lucky. So far Hampson hasn't succeeded in coercing his colleague Willard White into a swap.

He waxes lyrical about that song. 'It's one of Lenny's greatest moments . . . But I do think it's about much more than Whitman's homosexuality . . .' Hampson is poised for one of his earnest discourses. 'I think the poem has become something of a symbol or banner of his 'coming out'. But there's a higher level of awareness here. Freedom of self-expression was central to Whitman's philosophy. The joy, the liberty of going wild and free through the world. I mean, whatever stood in the way of his own personal expression pissed him off. That's the central issue, surely - the identity of self, regardless of sexuality . . . 'These men that travel with me . . .' - I find the impersonal pronoun very interesting there . . . It's too easy to abrogate the higher message; we've got to get out of the centre of our pants, for heaven's sake.'

But what did the composer think? He did after all set it sweet and low, a quiet confessional over solo cello and humming voices - the voices of comrades? 'I wish I'd been able to talk to him directly about it . . . I've been told he felt it was a repressed expression of a repressed subject. True, but repression of the subject is also repression of the self . . . You know the poem was written on the back of 'Democratic Vistas' - first edition. I think that's significant.'

Not so much an interview, more a debate. I now understand why Hampson is so irritated by criticism that is 'diatribe and not dialogue'. 'I'm talking about the kind of criticism that abrogates 100 per cent any credit for forethought on the part of the artist. I mean, we just wander out there like lost sheep to see whether we can please poppy or not] Well, I say fuck them.' Absolutely. Let's say what we mean here.

The downside of interviewing Hampson is the sheer volume of quality transcript you must reluctantly discard. He's an eloquent tour guide through the history of American song: you might easily be browsing through an old Yankee photo album. Then there's the American musical theatre in which he, like all red-blooded American baritones, has a vested interest: 'European operetta revolves around a tenor hero, but the American musical hero is pitched a perfect fourth lower]' Just imagine his Billy Bigelow in Carousel.

The recital platform is taking precedence over opera right now. But he is San Francisco-bound to play Valmont in the world premiere of Conrad Susa's opera of Les Liaisons Dangereuses alongside Frederica von Stade and Renee Fleming. Let's call it part of his campaign for new pieces rather than 'new' productions. He remains somewhat ambivalent about certain trends in opera production (I am gently reproached for referring to New York's Metropolitan Opera as 'a museum').

'Are we bored with the repertoire?' he asks, quoting an old Chinese proverb: 'Boredom is the endless search for novelty.' 'We keep colouring Easter eggs, trying to find a different way to put a different design on the same egg, while inside the whole damn thing has gone rotten or else is a completely empty shell . . . Did they say anything new about La Boheme? Well, maybe it's time to say - guess what, folks, we know what Boheme is all about. That decision becomes rather freeing. If we are so clever, so sophisticated that we can manipulate 200-year-old pieces into modern contexts, then we should be clever enough to write something in today's context. I'm not willing to put Don Giovanni in the Bronx or Cos fan tutte in Despina's Diner . . . but - and you can print this - I will read any libretto, any score for a 21st-century Don Giovanni. OK?' OK.

Thomas Hampson sings in 'Songfest': 7.30 tonight, RFH, South Bank Centre, SE1 (071-928 8800), broadcast live on BBC Radio 3

(Photograph omitted)