In 1987, Timothy Kain, head of guitar at the School of Music, dared to go where no guitarist had gone before. He and guitar-maker Graham Caldersmith dreamed of creating a guitar family, and so it was that Guitar Trek set out on a journey to explore new horizons in guitar music.

Twenty-five years later and with its fifth line-up of musicians joining Kain, Guitar Trek comprises Kain and three graduates of his course, Minh Le Hoang, winner of the 2010 Tokyo International Classical Guitar Competition, and Bradley Kunda and Matt Withers, who have also established a fine reputation as the Brew Guitar Duo.

Guitar Trek combines the fulsome sounds of the standard, treble, baritone and bass guitars. The range and complexity of such a union provides audiences with a repertoire as diverse as Brahms, Led Zeppelin, the Beatles, Handel and Westlake.

During its 25-year history, Guitar Trek has become recognised for their unique talent and innovative performances. This year, the quartet has been invited to perform at the fourth Adelaide International Guitar Festival.

The four-day festival has become a highlight in the Adelaide Festival Centre's calendar of events.

Guitar Trek will be in the company of some of the best guitarists in the world, including the John Scofield Trio, Ana Vidovic from Zagreb, Jason McGuire from Texas, Caminos Flamencos, Tommy Emmanuel and the Grigoryan Brothers. Overall, 88 musicians will present 42 events including recitals, masterclasses, including one given by Kain, workshops and artist talks.

The festival will also include the Australian International Classical Guitar Competition, which this year will feature four aspiring semi-finalists from the ACT, coincidentally all former students of Kain, who modestly claims an impressive number of former students are making their mark from Melbourne to Amsterdam.

After those early discussions with Caldersmith, it was five more years before Kain believed that the calibre of students passing through his course at the School of Music had reached a high enough level to consider forming a quartet that could explore the possibilities that the various guitars could provide. ''We aim for the highest standard - as good as you can get it.'' Kain says. ''It lifts them to another level. It's all that research-led practise or practise-led research. It's everything that a modern university would want to see happening in a department, and certainly at the post-graduate level.''

Not at the ANU apparently. In sweeping radical changes to the School of Music, Vice-Chancellor Ian Young has informed Kain that his position as head of guitar will be made redundant, resulting in Kain's departure from the school in September. The door has been slammed in the face of opportunity for guitar students of the future who aspire to the excellence that Kain has always encouraged.

In the light of recent developments and his imminent departure, Kain recalls with some nostalgia the ideals of the past

''The Canberra School of Music really did have an international reputation when I returned to take up the position after Sadie Bishop's retirement. I knew that I'd had a good education here, but I didn't know how good until I'd met other people from around the world. That was in 1975. Founding director of the School of Music, Ernest Llewellyn had a real philosophy of excellence in performance. It wasn't just something you mouthed.''

Guitar Trek premiered with a concert in the year that Andre Segovia died, in 1987, introducing their innovative combination of bass and baritone guitars made by Caldersmith, Kain's treble guitar made by Eugene Philp and the standards made by Greg Smallman, all of them renowned Australian guitar makers.

''They're all Australian guitars, Australian musicians, Australian repertoire with commissioned Australian pieces,'' Kain says.

''We packed out rehearsal room three,'' Kain says, ''and we had a big queue going back down to the front of the school so we repeated the performance half an hour later and it just went on from there.''

At the heart of Guitar Trek is newly commissioned Australian works and around that they put more standard classical repertoire, or World Music type repertoire, because the guitar allows for such a broad range of music.

''It's such a fabulous time to be a guitarist because the world has opened up to so many genres that the guitar sits in the heart of, and there's been so much cross-fertilisation in contemporary composition from so many other styles of music. Guitar sits beautifully in all that and it's an unhackneyed voice as well. It's fresh ground aurally and for composers as well. That makes it all a very stimulating world to work in.''

However, although the guitar is claimed to be the most popular instrument on Earth, once one enters the classical domain it can present very difficult challenges indeed. Audiences in Adelaide will have the opportunity to see how easy it might seem to be to master when they visit Guitar Trek's concert. It will start with the Waltz of the Flowers by Tchaikovsky - a favourite of Kain's mother and an intentionally popular work to engage the audience - and then to a quiet, reflective piece, To His Servant Bach, God Grants a Final Glimpse - The Morning Star, which is by Adelaide composer Graham Koehne. This will be followed by Philip Houghton's News From Nowhere, especially written for the guitar family.

The second half consists primarily of Nigel Westlake's Six Fish. It uses two standard guitars: a Dobro, which is one of those old Blues guitars with the metal front over it, and often played with a slide and a 12-string guitar. Originally the composition featured a six-string guitar, so the use of the 12-string guitar will be a noticeably different feature of Guitar Trek's version.

The second half will be rounded off with Bradley Kunda's new arrangement of Brahms' Intermezzo and then three short works by Spanish composer, Manuel de Falla.

On the final day of the festival, Guitar Trek will launch their latest CD, a 25th-anniversary collection of entirely Australian works in keeping with their ethos to promote Australian composers. It will include works by leading composers for guitar, Philip Houghton, Richard Charlton, Martin Wesley-Smith and Westlake's Six Fish, which gives its name to the CD.

Audiences at the Adelaide International Guitar Festival are in for a very special experience when Guitar Trek comes to town.

■ Adelaide International Guitar Festival, Adelaide Festival Centre from August 9-12. For further information and bookings phone BASS at 13 12 46 or visit adelaidefestivalcentre.com.au.