Here's their website: http://www.boulderacousticsociety.net/
Even if you don't think you like bluegrass or oldtime, you would like this band. It was one of the best groups I've seen in ages. I can't even describe it. It's a little bit jazz/country/dixieland/oldtime/classical. I mean the fiddle player is from Singapore, the bassplayer looks like a Bar Mitzvah boy (only I thought he was hot and I never thought Bar Mitzvah boys were hot) and the percussionist was playing a marimba and a bunch of other stuff. It was way way way cool.
Peter Rowan, who I do like was a snoozeathon by comparison, especially because he was doing all story/singer/songwriter ballads.
Please please please check this band out. They are just sooooo cool.