Americana kingpin Jason Isbell is always a gracious frontman and performer. But he had to stop his show with his band The 400 Unit a couple of times Tuesday at Wolf Trap in Virginia to take in what he was seeing: a nearly full outdoor amphitheater packed with fans who had been waiting as long as had to hear songs from his most recent album “Reunions,” released in May 2020.

Sixteen months later he was performing it as he intended before an appreciative crowd under a rising half moon. “Here we all are!” he marveled. “No screens!”

A lot of the new album’s songs were built for playing live and the first couple selections from his set, “Overseas” and “What’ve I Done to Help,” snarled with expressive guitar solos from he and guitarist Sadler Vaden. Both favor a kind of wild, electric slide tonality echoing the best of 70s inventiveness from Duane Allman to David Lindley.

Isbell has attracted wide attention with his songwriting, though, with compositions full of the kind of detail and turn of phrase that can stun midway through. 

With his wife Amanda Shires back in Nashville recovering from an unnamed malady, it’s tempting to say the band played harder and tilted more toward rock than they might have had she been there with her countrified fiddle and backing vocals. Vaden added Pete Townshend-style windmill slashes to his guitar more than once, which might have triggered drummer Chad Gamble rumble like Keith Moon, while bassist Jimbo Hart conjured up a bass solo or two in the tradition of John Entwistle.