It was founded by Alex Poots and David Sefton to bridge the divide between the classically oriented Edinburgh International Festival and the inherent comedy and theatre of the Fringe.
It worked spectacularly well. Last year Poots and Sefton waltzed off with the Scotland On Sunday Critics Award For Music for a collaboration between Michael Nyman and The Divine Comedy. This year, Spiritualized and the feted classical composer Steve Martland are scheduled to perform new vocal and conceptual pieces together on the opening two nights.
David Sefton is head of artistic development at the South Bank (following an early stint as a writer for the defunct music tabloid Sounds). He says: "I'd go to the Edinburgh Festival every year and see what was going on. They were great on theatre, fine on classical music, but there was absolutely no recognition of contemporary popular music at all. Punters would go for the cabaret and the theatre, but I just thought `Where's the music?' You'd be lucky to get Ray Davies.
"So that's where it all started... I'm very, very pleased at the bill we've put together for this year's event."
Sefton admits to an admiration for all the artists on this year's roster. It raises the question of how much influence he and Poots have over the general content and structure of the whole event, particularly as they try to encourage the acts to be more adventurous than they would on a normal tour.
"It's enthusiasm that drives what you do," he explains. "We book the acts and then we talk about what they do. I went to the first rehearsal of the Spiritualized/Martland project last night, and it was great, fortunately. You have to put people together who you think are going to work. I don't know what happens when they don't - that's a bridge I'll cross when I come to it.
"There are `straight' gigs in there, but they're programmed because they're interesting people: Asian Dub Foundation will do what they do, but will also support themselves with a DJ set. Everyone is encouraged to do something a bit wacky. Nick Cave is doing a solo show that's never been seen in the UK before, accompanying himself on the piano, with elements of spoken word."
The artists themselves are keen to banish their own preconceptions. Everyone is seemingly unconcerned about the potential for tarnished reputations; pretension quickly evaporates into a maverick spirit of adventure.
Neil Hannon (Divine Comedy) recalls how last year, after agreeing to work with Michael Nyman, he was "equally intrigued and terrified by the idea". It took two months to arrange and learn the new material, a period through which the singer claims he was "driven partly by a fear of being crap, and partly by a fear that Michael wouldn't like what we'd done to his songs."
The ensemble played at the Jaffa Cake, a venue with "no air conditioning and a stage the size of a handkerchief... we played three shows over two nights, and I can say without any doubt that they were two of the hottest nights of my life, and two of the most exhilarating.
"The crowded Jaffa Cake only added to the atmosphere - it was an experience I wouldn't have missed."
Sefton says: "The festival context in Edinburgh makes it very clear that this is not just the latest tour by a person or a band, and so it allows the possibility for space and experimentation. They're performing in a place where people expect weird things to happen. For the most part, the artists embrace that and think `We can go there and take chances'."
One of Sefton's great strengths is his ability to transmit his enthusiasm to others. It comes across as he says: "Spiritualized/Martland is going to be fantastic. Getting John Zorn into the country after he said he'd never come back is great. The Jesus And Mary Chain haven't played in Edinburgh for 10 years, so that's going to be wild. The Delgados and Six By Seven are also playing - The Delgados are one of the best bands in the country, and Six By Seven have made one of the best records of the year. With Nectarine No 9 on the same bill, there will not be a better gig put together in the whole of the UK this year. Last year we did Mogwai, Urusei Yatsura and The Delgados on that triple bill, and it was just an awesome evening."
With PJ Harvey and Nick Cave already sold out, and David Thomas, Yo La Tengo, Roddy Frame and the New York electro-artist Ben Neill also appearing, it promises to be an astonishing two weeks.
The Flux Festival, 14-29 August at the Jaffa Cake and the Queen's Hall. Tickets from the Queen's Hall (0131-668 2019; credit card bookings 0131- 667 7776; Fringe booking office 0131-226 5138)