As Ben Haggerty – aka rapper Macklemore – reminds us during one of his many asides, it's just two years since he and collaborator Ryan Lewis played to 200 fans at a tiny club down the road. Of course, that was before 'Thrift Shop', a monster smash that has clocked up nearly 500 million YouTube views and, by its video, is in imminent danger of turning the mangy fur coat into an ironic fashion statement.
Overnight, the song has transformed the Washington State partnership (pictured) into a major force in hip-hop.
Big all over, in Ireland they seem especially adored, which may have to do with the country's long-standing love affair with bubble-gum rap but is probably accounted for by the fact that Haggerty is a green beer-swilling Irish-American straight out of St Patrick's Day on Fifth Avenue (or at least he was before turning teetotal).
The crowd is a sea of tricolours and Hollister hoodies as Haggerty (wearing an Ireland rugby shirt) and Lewis, in a DJ booth high above the audience, plunge into 'Ten Thousand Hours', the epic opener from their new album, The Heist.
Heartfelt and self-consciously celebratory, it is far more typical of their output than the lightweight 'Thrift Shop' – bravely they dispense with their uber-hit just three tracks later, as if trying to clear the air and ensure the rest of their catalogue is not unduly overshadowed.
As a conjurer of beats, Lewis is efficient and unshowy. Haggerty, on the other hand, has a tendency to gush. One of those lyricists who believes it is their job to address Big Issues, no matter how pedestrian their insights, his honesty can veer into preachiness, as demonstrated by the anti-drug paean 'Starting Over' and gay marriage anthem 'Same Love' (a laudable tune that commits the error of talking down to the listener).
With a set covered in fake camouflage and a saxophone player in a kilt, there's little of the blaring braggadocio usually de rigueur in arena hip-hop shows and, though he does go on a bit, between numbers, Haggerty strives for a genuine connection with the crowd. The music, for the most part, is unabashedly uplifting, though there is the occasional cringe moment – accompanied by spumes of green confetti, begorrah-riffic tankard-clinker 'Irish Celebration', in particular, would make a leprechaun's toes curl.
For all that, the duo's hearts are obviously in the right place. They appear deeply grateful for their success and appreciative of their fans.
That's not enough to guarantee a career once the 'Thrift Shop' buzz has died but it probably means they are well equipped to deal with whatever happens next, whether that be ongoing popularity or a swift return to obscurity.