'I'll choose what's next," David Grubbs sings repeatedly on the opening cut of his latest album, "A Guess at the Riddle." The Kentucky-born guitarist seems to accept the inevitable, which is one way of looking at his unusual career. Having begun by making fairly conventional indie rock in a group called Squirrel Bait in the '80s, he went on to become a pioneer in Chicago's experimental instrumental scene, first with Jim O'Rourke in Bastro and then with postrock god John McIntire in Gastr Del Sol.

Since going solo, though, in the late '90s his ambition has been to become a sensitive singer-songwriter. That may sound like a step backward but, as with the purely instrumental work, his songs are mainly notable for their heavy atmosphere, which recalls Neil Young's late '70s ouput. Grubbs' guitar playing is nuanced and wholly original, and not just on the handful of quirky instrumentals he offers up like shiny coins on the new album.

With a voice that's almost requires you to listen to it and a poetic sense that elevates enigmatic epigrams as the ultimate verbal accomplishments (the entire lyric to "Kentucky Karaoke," from his last album, goes "Here's a prediction: when you have stories to tell, you will tell them"), Grubbs seems less interested in making a point than in making an impression. There's a pleasing airiness to his songs, a feeling that they will evaporate once he stops playing them and no one will ever call them back. Every moment counts, so listen carefully.