I Fagiolini may be called “The Little Beans” in Italian, but they make a big, beautiful choral sound.

I’m dying to ask Robert Hollingworth what it’s like to conduct Spem in Alium. Golden strands of vocal polyphony in no less than 40 parts weave their way through Thomas Tallis’s sublime masterpiece of the English Renaissance, which will be performed by Hollingworth and his British group I Fagiolini at the Perth Festival this week. Does he ever feel overwhelmed in the face of that rich choral tapestry? Conducting in the round as luminous voices wash over him, does he ever want to throw down his baton, close his eyes and simply soak up the sound?

“Actually, it’s like driving a monster truck,” he says gleefully. “The forces are so enormous.” Hearing his refined Oxford accent and clear singer’s diction over the phone, it’s hard to imagine him driving anything gutsier than a Volvo, but then, it’s easy to underestimate the power of this magnificent Tudor motet, in terms of sheer size and emotional impact.

“Enormous” is relatively new to I Fagiolini, a band of singers long associated with Monteverdi madrigals and intimate Renaissance repertoire. So what made them decide to supersize?

“The work intrigued me,” says Hollingworth. “It has this aura of grandeur and majesty, but it is also this intimate conversation between the five eight-voice choirs that make up the piece. It’s this conversation that is fundamental to all small ensemble work that I like. The same challenges to the ensemble player are still very much there.”

For the Perth performance, eight core members of I Fagiolini sing the most florid lines (“like ivy around big harmonic pillars”) while the local St George’s Cathedral Consort beefs up the other parts. Hollingworth recalls that “the first rehearsal was about trying to give people a view of the work outside of their own choir, so they could see what direction the animal was going in.” Unusually, an orchestra of brass and period strings doubles the choir, which he insists is “a completely authentic thing that helps bring out the individual lines of polyphony”. It is with the added clarity and splendour of instrumental forces that Hollingworth recorded the work in 2010.

The album was a surprise hit, achieving phenomenal success rarely associated with classical (let alone choral) sales and drowning out the clamour of Eminem and Bon Jovi in the British charts. It wasn’t just Spem in Alium that captured the public’s imagination; it was the world premiere recording of a companion piece by the little-known Italian composer Alessandro Striggio, written some 40 years before Tallis’s famous magnum opus of c1570. As if 40 parts weren’t enough, Striggio’s Missa Ecce beatam lucem swells to an staggering 60 in the final movement.

Though a deeply spiritual and uplifting work, it’s ideally suited to the excitement and extravagance generated by a citywide arts festival, and ‘bigger is better’ applies in today’s society as much as it did in 16th-century Florence. Hollingworth explains: “You have to see a piece like that in its social context. It’s basically what happens when you throw money at something. The Medici court had vast sums of money to spend and they went for spectacle. And this is an example of music with that kind of spectacle and gigantism.” How could such a monumental choral work have been languishing unheard by modern ears for so long?

“It was miscatalogued,” Hollingworth sighs ruefully. “Someone came along and saw it said ‘40 voices’ and thought, ‘That can’t be right,’ and crossed the zero out.” Although posterity has been kinder to Tallis, Spem in Alium was in fact inspired by his Italian predecessor’s work in an ambitious case of musical one-upmanship. But if Striggio was somehow cheated out of his rightful place in the Renaissance firmament, Hollingworth is adamant that it wasn’t because the mass is inferior or less accomplished in its polyphonic writing. “It’s like saying, ‘Do you prefer a short black or a glass of red wine?’ Tallis is much more contrapuntal than Striggio; it’s more dissonant – in a good way – but Striggio probably would have criticised Tallis for that and would have said it’s too dissonant and doesn’t obey the rules as much. Striggio was the one with the idea who showed it was possible, but people often improve on invention, and that is what Tallis set out to do.”

Similarly, following the success of the album, I Figiolini have set out to outdo themselves. Seemingly now addicted to massed choirs, Hollingworth has led them in a follow-up recording of large-scale Italian Vespers including music by Giovanni Gabrieli, to be released in May. And in a separate performance at the Perth Festival, they unveil their latest project How Like an Angel: a collaboration between the chamber singers and Circa, an innovative troupe of acrobats. Vocal music from as far back as the 11th century isn’t the kind of thing you would expect to go down well at the Cirque du Soleil, but Hollingworth says that the incorporation of music, theatricality and corporeality is an attempt to “break down Renaissance polyphony.

“The danger with all this lovely music is that it’s just a nice noise. We try to let people inside that world. It’s unusual for Renaissance groups to do ‘shows’ – they usually do concerts. But we’re trying to get to the heart of what the polyphony is really about, and to what extent you can physicalise sound.”

I Fagiolini have been presenting these unconventional “shows” since Hollingworth founded the group out of Oxford in the late 1980s. Unlike most of their “serious” colleagues in similar ensembles, they weren’t afraid to be tongue-and-cheek about the venture, right down to their name: At first, Hollingworth recalls, they were going to call themselves “The Beans” because of the stereotype of early music practitioners as lentil-loving Renaissance Fair devotees (Hollingworth himself was nicknamed “Beany Bob”). Given the choir’s predilection for Italian repertoire, someone suggested the worldlier translation of “I Fagiolini” and the name stuck, even though it turns out to have a salacious slang connotation in Italian that gets them into hot water on tour.

Since the early days, the ensemble has played with the traditional format of choral performance. On their DVD The Full Monteverdi, the singers are depicted singing passionately to each other as couples in the throes of public split-ups and private heartbreak. Their next project, Tallis and Wonderland, similarly aimed to “bring works to the public that they haven’t heard before, that are unusual in some shape or form”.

The ultimate goal is to help listeners discover and comprehend more of the wondrous details buried within the music. Hollingworth wants audiences to hear beyond “the surface sheen of the noise. People will hear the conversational nature of it – it’s like having five people in a room shouting, and sometimes they shout together and sometimes they shout at different times – and trying to make that into something that makes sense.

“I know nothing about rock music, so when I hear rock I just hear the noise it makes; I can’t tell one group from another. A lot of people will be the same when they listen to Renaissance music.”

So while it’s unlikely I Fagiolini’s next show will be “Rock meets Renaissance”, we may reasonably expect a monster truck to make an appearance.

I Fagiolini sings Tallis’s Spem in Alium and Striggio’s Mass for 40 voices at the Perth Concert Hall February 27, and perform in How Like an Angel on February 29. Read Limelight’s CD review of Spem in Alium here.