"If you want to bring on a special musical guest, you can't do better than this," David Letterman said on Tuesday's 'Late Show,' introducing Andrew Bird's performance with Tift Merritt. Those words were met with very sparse applause -- not because the audience wasn't into Bird and Merritt, but because there was no audience, thanks to superstorm Sandy. But despite the virtually empty Ed Sullivan Theater -- or “a big ol’ empty barn,” as Letterman called it -- it was decided that the show must go on.

And that it did, with Bird on violin and Merritt on acoustic guitar, joined upright bassist Alan Hampton. The trio turned in an equally sparse and totally gorgeous cover of 'If I Needed You' by late country-folk singer Townes Van Zandt. The cover is featured on Bird's new album, 'Hands of Glory,' which dropped this week.