Although he had never studied the role of Shadow before being offered the part in this revival of Robert Lepage's production (first seen at Covent Garden in the summer of 2008), Ketelsen almost falls over himself with excitement talking about the experience. "I've had to study it longer than any other role, for some reason. Just a few small things like, oh, the music and the rhythm and the pitches – you know, inconsequential things like that!" And although he says that his native language isn't his favourite in which to sing, he is relishing the 'flowery' English of W.H. Auden and Chester Kallman's libretto: "It's fun to spit out posh words that I never use, like "dilatoriness" – I had to look that one up!"

The cast have just finished staging rehearsals, and Ketelsen's eyes light up when he talks about the production. A big cinema fan, he reels off scenes from several classic films to which Lepage has alluded, and gushes about the use of simple, yet convincing, visual effects in the set: "It makes me happy to watch, it's a lot of quality eye candy." Ketelsen is equally effusive about his colleagues: "Toby [Spence] is fabulous: super-intelligent, great performer, and great voice, great acting – someone I would consider the Tom Rakewell of today. And Rosy Joshua [singing Anne Trulove] does things with her voice that I wish I could do, just float a little high note for ever and be beautiful. Then when it's my turn I just get up there and let it all out – roar!"

There seems to be a great camaraderie amongst the cast, too, judging by Spence's enthusiastic documenting of the rehearsal process on Twitter. (Ketelsen is there, too, giving his own slant on things: follow kyleket and RoyalOperaHouse to keep up with developments.) Over the last few years the resident of Madison, Wisconsin has somewhat cornered the European market in his signature roles of Figaro (Mozart's), Leporello and Escamillo (the one part he has sung more than any other); his rich bass-baritone is fast becoming a frequent presence in many of Europe's leading houses, including the Liceu in Barcelona, Munich's Bayerische Staatsoper – and, in particular, Covent Garden, a venue he has called 'a home from home' in the past.

Was it a conscious decision of his to spend so much time singing on this side of the Atlantic? "Well, it's horrible because it's so far from home, but it's wonderful because you can see London and Paris and Barcelona and Madrid and Hamburg and Munich and Rome – it's a great experience and I'm working at wonderful houses." And while he ultimately wants to be singing more in the USA, his view is that many American houses prefer to employ 'exotic' European singers in order to sell tickets – he sees himself as 'just another in the long line of American artists to do this: you'll go to Europe and you'll sing there for 10 years or something and only then will you start to get noticed back in the US.'

Inevitably, being away from home and family – wife Rebecca and children Melanie and Benjamin – is the biggest drawback. (Back in 2005 his wife went into labour with Benjamin while Ketelsen was in London singing the part of Henrik in the ROH production of Nielsen's Maskarade – he flew back to Wisconsin to be present at the birth, then immediately returned to London to resume his role.) His children are too young to travel to watch him, and although the whole family will enjoy a Provençal summer together this year while Ketelsen sings Leporello in the Aix-en-Provence Festival, they mostly get to hear him singing at home. Ketelsen jokes that when his children complain, "Dad, it's loud!' he retorts, 'Yeah that's right, it's loud, and that loud built this house."

He professes to being absolutely content with his core set of favoured operatic roles for the foreseeable future: "With my Fach, I have a luxury in that as long as I can keep my voice going, I'm more likely to sing for a longer time. I guess Leporello is one of those roles that you can do for a long time – the Fach just has longevity built into it." But Ketelsen is aware that he has youth on his side: "I'm 38, and they say that for basses and bass-baritones the 40s is their prime." He claims that Giorgio Tozzi, the distinguished American bass and Ketelsen's former teacher, has been badgering him to move into weightier repertoire – Scarpia, in particular.

Ketelsen isn't so sure, though, that the time is right to take on something so heavy. "It's a short role, but it doesn't feel like a short role. I've never sung it through – I've done the Te Deum, which almost killed me! Puccini is one of my favourites, but he didn't write enough for bass." He refers at this point to Samuel Ramey and to the similarities between their voices. "Ramey waited until he was in his 60s to do Scarpia for the first time – I think that was only about six years ago – so I look forward to doing that."

While Ketelsen didn't set out to copy Ramey's career – 'more a template to refer to' – he is happy to admit that he is looking in similar directions to his elder colleague. "One thing I'd like to do sooner rather than later is to get into virtuosic roles of Handel and Rossini – something that takes advantage of coloratura, but some people say, 'Are you going to go into Wagner' and I have no idea – who knows? Right now I would say there's no reason to think that I would, but 10, 15 years from now? I wouldn't rule it out."

All of which sounds like the contented musings of a man more than happy with his lot and his prospects; is there anything else that he would leap at the chance to do? Musical theatre, is the slightly unexpected answer – another legacy Ketelsen has inherited from Tozzi, who provided the singing voice for the part of Emile de Becque (acted by Rossano Brazzi) in the film of South Pacific. "You know, I was recently asked to audition for South Pacific on Broadway, but I only had three weeks' notice – it was a tragedy! The Broadway people are going back to a lot of these shows' roots – they were written with classically-trained singers in mind – but perhaps need to realise that opera singers are generally booked a bit further in advance…"

So, I ask, where will he be appearing the next time he visits London – Covent Garden or somewhere in Theatreland? "Maybe down the West End – wouldn't that be great?" Shaftesbury Avenue – take note.

Kyle Ketelsen appears as Nick Shadow in the Royal Opera's revival of Robert Lepage's production of The Rake's Progress from 22 January.