During their 2009 Savannah Music Festival performance, the Punch Brothers reached deep into their considerable bag of tricks and produced one seriously unexpected rabbit: The Beatles’ “Martha My Dear.”

This time, they played “Paperback Writer.” Five-part harmony and that old, familiar riff played on acoustic guitar and banjo. Yow.

A string band that’s strongly rooted in bluegrass, the ‘Bros delight in taking the old form and turning it over, under, sideways, down, on its ear and on its head. The results are always creative and stimulating – the guys are all gargantuan players – and there wasn’t a single tune in the band’s April 2 Trustees Theater set that didn’t show a polished virtuosity.

Move over, Bill Monroe, and tell Carter Stanley the news.

And that’s a good thing – innovation and incessant forward motion are necessary to the health of music.

The band’s Trustees set included the Strokes cover “Heart in a Cage,” Josh Ritter’s moribund maritime ballad “Annabel Lee,” Gillian Welch’s sprightly “Wayside” and a handful of quirky, original Punch tunes, from the humorous (“Next to the Trash”) to the heartbreaking (“Alex”) to a new and as-yet unrecorded “suite” (“Calm Before the Storm,” if I heard the title correctly).

So here’s to you, Chris Thile.

The grown-up former prodigy who formed and leads the Punch Brothers, Thile seems to have found new notes and chords on the mandolin, and he plays the instrument as if it were an extension of his arms.

Thile is one of those musicians – and there are more and more of them these days – who delights in expanding the capacity of a given genre, using jazz, classical and rock ‘n’ roll themes and figures to expand his vision. This is why his music is called (for those who must have a label on something) “progressive bluegrass.”

Onstage, Thile is a whirlwind. Although all five members of the string band stood the entire night, in a semi-circle around their microphone stands, he was the only one that moved significantly. He was never still, dancing like a plucked chicken, getting in his stone-faced bandmates’ mugs as they soloed, yodeling into the mic until his eyeballs seemed about to pop.

Of Thile’s musicianship and vision, there can be no question. He is clearly an uber-talented player, and the Punch Brothers are doing things with acoustic music that the pioneers of bluegrass could only dream of.

Yet he also came across smug and just a little too self-aware onstage.

The concert was a most impressive performance of virtuosity, although strangely soul-less; I felt as if I’d just come out of a museum tour, or had listened to a really good lecture. I left the theater with an empty feeling.

Thile will make his fourth consecutive Savannah Music Festival appearance in 2012, it was announced before the show.

Take from that what you will.

This article appears in Mar 30 – Apr 5, 2011.