"I'm feeling so embraced," says dapper bluesman Eric Bibb, taking his turn in the spotlight during a typically jammed Transatlantic Sessions setlist. This is traditional music's foremost multi-artist love-in, and the 2013 incarnation radiates warmth and wit, perhaps taking a cue from founding members Aly Bain and Phil Cunningham, Scottish folk's most enduring bromance.

Originally conceived as a TV showcase in the mid-1990s, Transatlantic Sessions has become a keystone of Glasgow's annual Celtic Connections festival and recently expanded into a national, and international, tour. "Supergroup" doesn't cover it – with 17 artists in rotation, this is more like a mega-troupe. But filling your squad with global roots galacticos such as Bibb, Mary Chapin Carpenter, Teddy Thompson and Appalachian wizard Bruce Molsky would be for nothing unless they could function as a unit.

The master-stroke is locating the green room refreshments and couches on stage, so even when the group is pared right down – as when Crooked Still vocalist Aoife O'Donovan sings the haunting Hollowell, accompanied by piano and backing vocals from Carpenter and Scottish songwriter Emily Smith – the other musicians remain as visibly rapt as the audience. From Cajun dancehall to Scottish airs, there is a sense of common purpose and appreciation that helps give this patchwork gig a tangible throughline.

With the band reconfiguring for each singer, there is also a slight sense of endless musical chairs, but Dobro maven Jerry Douglas acts as de facto MC, cracking wise while cracking the whip. The evening builds towards a massed rendition of Down at the Twist and Shout, Carpenter's breakthrough hoedown from 20 years ago, its original radio-friendly facets pleasingly gritted up by the ensemble.

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