It doesn't do to prejudge these things, but the five stars at the top of this review were in place within a few minutes of Punch Brothers easing into their opening number, Movement and Location.

A song about baseball, it exuded restrained instrumental mastery, keen vocal expression with a startling variety of colour, a rarefied sense of dynamics and an all-round feeling of wellbeing. And then things got even better.

Welcome to the ultimate 21st-century bluegrass band. The quintet shy away from such stylistic labelling, and there are those who would consider it treachery. But bluegrass instrumentation and an innate feeling for the genre – as evidenced by guitarist Chris Eldridge's tears in my beer singing of the Seldom Scene's Through the Bottom of the Glass – give them their starting point for a musical adventure that can slip from abstract strum and twang to raging traditionalism apparently at the flick of some unseen switch.

Their interplay is awesome, with Chris Thile's mandolin producing torrents of sweetly struck, super-high-speed, mega-creative runs, fiddler Gabe Witcher adding fluent bite and Eldridge and banjoist Noam Pikelny matching the pair of them while Paul Kowert holds it all together on bass. What makes their music all the more pleasurable is the roguish sense of fun they bring to their most highly complex arrangements. From the richer than rich four-part harmony vocals on their bluegrassification of the Strokes' Heart in a Cage to Patchwork Girlfriend's throwaway vaudeville brilliance and on to Thile's liquid solo Bach interpretation during the encores, this was the sort of event for which the term gig of the year was coined.