Around the world in 153 concerts ... joining the dots from Africa to Ireland to America to Scotland

Today, that figure has roughly trebled, and Celtic Connections is an 18-day colossus bestriding the ­international music scene, responsible for a hefty spike in the local low-season tourist trade. Hard as it would once have been to credit, considerable numbers of people from around the world now book holidays in Glasgow in January.

This year's imminent cornucopia of music is as expansive, adventurous and discerningly curated as ever; a spectrum of sounds ­spanning all the way from Congolese cult legends Konono No 1, with their scrapheap-salvaged instruments and mesmerically distorted grooves, to the compositional canon of the late Hebridean hero Pipe Major Donald MacLeod MBE, arguably his instrument's greatest tune-maker of the 20th century.

Headline highlights in between include league-of-his-own icon Van Morrison; the live premiere of Usher's Island featuring Irish folk royalty Donal Lunny, Andy Irvine and Paddy Glackin; the blockbusting music of Scottish film composer Craig Armstrong; red-hot US rising star Chastity Brown (as seen on Jools Holland last October), and a star-studded celebration of Ewan MacColl's music, marking a century since his birth.

It is the ninth edition of Celtic Connections to be programmed by Capercaillie co-founder Donald Shaw, whose most oft-noted ­innovation during his directorship has been a significant increase in the presence of roots-based artists from beyond the Celtic territories and their transatlantic diaspora.

As this strand within the line-up has developed, so has it deepened and diversified, such that alongside established world-music heavyweights like Beninoise diva Angelique Kidjo - performing bespoke orchestral arrangements of her back-catalogue with the RSNO - and gypsy kings Taraf de Haidouks, an array of other acts highlight how traditional and contemporary genres are being fruitfully cross-fertilised around the globe.

The aforementioned Konono No 1, who combine folk instrumentation, dancers and chanted vocals with a sound system fashioned from discarded car parts and kitchen equipment, have been creating their unique "Congotronic" sound since the 1960s, winning over fans of arcane electronica and avant-rock as well as African music devotees. Nigerian pioneer Orlando Julius is another veteran survivor, here performing both decades-old classics and material from last year's Jaiyede Afro album with quirky London jazz/funk combo The Heliocentrics.

The dazzling Venezuelan pianist Leo Blanco also inclines in a jazz direction, and reunites in Glasgow with the sterling Scottish-based trio of Paul Towndrow, Mario Caribe and Alyn Cosker, building on their first alchemical collaboration in 2007.

Having first emerged as a leading light of Sao Paulo's underground hip-hop scene, Brazilian MC Criolo is now extending his poetic, ­polemical message across the international dancefloor, while his native sounds are also mixed into freshly inventive forms by top London collective Da Lata, who feature in the triple-bill World Beat Bothy, a live club night at The Arches.

Among other first-timers at the festival, a top contender for this year's most talked-about act is Italy's Canzoniere Grecanico Salentino, a seven-piece ensemble from Salento, in the country's boot-heel, whose electrifying marriage of music, song and dance explores and celebrates the ancient, ritualistic tradition of tarantism.

In a temptingly contrasted double bill, they're paired with South African a cappella quartet Complete, championed by Hugh Masekela and hailed as the country's next big singing sensation.

In keeping with the festival's signature goal of finding and forging musical connections, it nowadays not only books such international artists but enables them to perform and collaborate with their Celtic counterparts.

A prime example this year is a lavish four-band bill called Wired to the World, which sees Glasgow's own mighty Treacherous Orchestra (a direct product of Celtic Connections' melting-pot energies) launch their brilliant second album Grind, in company with the magisterial Michael McGoldrick Band. They're joined by Damon Albarn proteges Songhoy Blues, who embody a vibrant, defiant microcosm of Mali's cultural diversity; and the exceptional Cameroonian singer Coco Mbassi, with her subtle, playful blend of African, gospel, jazz and soul influences.

The magical, near-telepathic interplay between Welsh and African harps, in the hands of Catrin Finch and Senegalese kora maestro Seckou Keita, is already on the radar of many cognoscenti thanks to their rapturously-reviewed duo album Clychau Dibon a year or so back. Equally full of intriguing promise is Lahore Ceol Mor, which unites the trio led by award-winning young Gaelic singer Mischa Macpherson with three Pakistani musicians, a project originally created for last year's Commonwealth Games festivities and here given the chance to develop further.

There's more celebratory fraternising between Scotland and the subcontinent when veteran Edinburgh folk fusioneers Shooglenifty, toasting their 25th birthday and their eighth album, The Untied Knot, team up with the Dhol Drummers of Rajasthan.

Thanks to the good offices of Showcase Scotland, the annual music-industry expo staged right in the thick of Celtic Connections, 2015's programme includes a yet further-flung international element, in the shape of half a dozen highly varied artists from New Zealand, the event's partner country this year.

The biggest name is the platinum-selling Trinity Roots, renowned for their hypnotic, freewheeling blend of Maori, reggae, blues and funk, and their enthralling live performances.

Others include the hugely charismatic Horomona Horo, with his contemporary take on the haka and traditional taonga puoro instrumentation; Weissenborn guitar prodigy Thomas Oliver; dreamy folk- pop outfit Tiny Ruins and singer-songwriter Maisey Rika.

While it is often the case that Celtic Connections' globe-spanning reach and diversity attracts the most attention - including the negative variety, like the surprisingly oft-heard complaint that this world music stuff is all very well, but what about Scotland's own music? - the festival's bedrock, backbone and foundations remain overwhelmingly homegrown.

A count through the programme reveals that of 153 concerts in total, fully two-thirds - 103, to be precise - contain at least a substantial Scottish component, ie the support act as a minimum. And as the brisk year-round business facilitated by Showcase Scotland attests to, in exporting Scottish acts around the world, the festival provides them with the ideal high-profile, high-production values platform to parade their wares, be it in the form of bold new cross-genre collaborations or intimate celebrations of cherished tradition-bearers.

A prime example of the latter this year, for instance, is a concert in honour of the revered Gaelic singer Mairi Smith, a real musicians' musician - especially as she's never released an album - with Julie Fowlis and Ireland's legendary Ni Dhomhnaill sisters also on the bill.

At the other end of the scale, there is the cast-of-thousands extravaganza The Bruce 700, piper Allan MacDonald's acclaimed musical re-imagining of Bannockburn, originally performed to commemorate last year's anniversary.

Also on a commemorative theme, as well as the opening concert's live orchestral premiere of Grit, by the late Martyn Bennett - who appeared at that very first Celtic Connections, back in 1994, in his original solo guise, and later launched his band Cuillin at the festival - the great and good of British folksong will gather in homage to the pivotal figure of Ewan MacColl, with the likes of Dick Gaughan, Martin and Eliza Carthy and Karine Polwart inaugurating his centenary year.

The ever-expanding and diversifying Americana scene has been richly represented at Celtic Connections since its early days, with this year's offerings including two of the key acts who helped unite the genre with indie/alternative cool, Lambchop and Calexico, as well as thrilling post-bluegrass quintet Punch Brothers, scorching rockabilly reinventor JD McPherson, and the joyously jiving California Feetwarmers.

And as if it weren't enough to reach across almost every style of music, the festival also encompasses other art forms, most strikingly this year with The Second Coming, at the Tramway, a spectacular merging of music, spoken word and aerial dance celebrating WB Yeats's life and work. There's also a revival of Elspeth Turner's play The Idiot at the Wall, based on the traditional "cruel sister" ballad and interwoven with Gaelic songs, and the biggest staging yet of Irish singer Michelle Burke's highly successful show Step Into My Parlour, a sweetly nostalgic revisiting of bygone house-ceilidh craic. And for those of a cinematic bent, King Creosote and his band will be performing the live soundtrack to Virginia Heath's hit archive collage of last year, From Scotland With Love.

If your post-Christmas blues survive that little lot - and the rest - then the case is probably terminal.