Ryan Adams showed off his best and worst qualities at Strathmore on Tuesday. (Photo by David Black)

After Adams spent two hours living up to his reputation both as a flaky, distracted performer and as a superb songwriter with a stunningly clear and nimble set of pipes, Isbell joined him on stage. (Isbell had begun the long evening with his own strong if too-brief set.) The two Southern men bantered while unhurriedly working out what to play. We’d grown accustomed by this point to lengthy intervals while Adams flipped pages in his dog-eared songbook and floated anecdotes that dissolved (“I don’t know where I was going with that)” more often than they landed.

Isbell took the lead, playing “Danko / Manuel,” the third song of the night he’d recorded with the Drive-By Truckers, the group he left in 2007. Adams answered with a tune from his old band, Whiskeytown’s “Jacksonville Skyline.” They ended the evening attempting to out-growl one another on a jocular cover of Alabama’s “Love in the First Degree.”

It was a finish that nearly lived up to the show’s breathtaking start. The Strathmore is the region’s best-sounding room for singer-songwriters, and Adams, having dissipated the promise of his fantastic early records (like 2000’s “Hearbreaker,” well represented in the set) with too many mediocre ones since, is the ideal patient for its rehabilitative properties. The “Oh My Sweet Carolina” he opened with was heart-stopping, and the title track of his new “Ashes & Fire” album that followed seemed to hail from the same inspired country.

Eventually Adams lost focus, and his indecision invited spectators to start calling out requests. Sometimes these prompted record self-reviews (“I hate every [expletive] song on that album,” of 2003’s “Rock N Roll”), sometimes improvised tunes: “I Got a Plan” mocked the very notion that he’d spend the moments preceding a gig playing basketball instead of making up a set list.

Then he screwed up the very next song he tried to play.

These exchanges felt playful rather than confrontational. And every time Adams managed to settle down enough to actually perform one of his sad and lovely songs, it was easy to forgive the jittery, talky process that had got him there.