In a town seemingly crawling with talented young guitarists, John Jennings, one of the best, is still a comparative unknown and something of an enigma.

Talk to any of the local guitar heroes of his generation -- blues 'n' boogie man Jimmy Thackeray, for example, or Sturm und Drang master Stuart Smith, who won a recent Wammy for best area rock guitarist -- and you'll find some of Jennings' biggest admirers.

"There's no doubt in my mind," says Smith, who dedicated his Wammy to Jennings. "He's the best around."

But it seems as if the 32-year-old guitarist has gone out of his way to remain in the shadows, particularly in the last few years. He'll make one of his rare appearances at a showcase at the Birchmere tonight.

"It's true," Jennings admits. "I haven't been Mr. Visibility. But I've been keeping busy -- in the studio and working on other people's projects."

Jennings is also highly thought of as a singer and songwriter, whose highly compositional and melodic tunes have a sophisticated scope and breadth few others can match.

Says John Carroll, no mean songwriter himself (he wrote "Get Closer," the Linda Ronstadt hit): "John's songs will move you: As far as the lyrical and musical content, they're so listenable. I love them."

"Country Roads" coauthor Bill Danoff agrees. "His songs are first rate, and he sounds like no one but himself."

And yet Jennings has not led his own band for more than five years, since he terminated Big Yankee Dollar, a group that made a small but reverberative splash on the old Cellar Door/Columbia Station/Mr. Henry's club circuit. The band, which featured mostly Jennings' tunes, lasted barely a year. He walked away from it for what he says were personal and musical reasons.

Why not form a new working band? "The local club scene can no longer support a new band playing original music," he says. "You just can't do it anymore."

Instead of leading a working club band, he decided to hone his talents in the studio, and became a much-in-demand studio player. He also has worked as a sideman in already established local rock and folk groups.

Clubgoers might have heard his acoustic work with Mary Chapin Carpenter, as well as a number of performers who appear at the Birchmere, including Kate Wolf and Jonathan Edwards. He also has played electric guitar with the Rosslyn Mountain Boys, Metro and Good Rockin' Tonight, among others.

The effortlessly eclectic guitarist Pete Kennedy has worked with Jennings both in Good Rockin' and in the studio. The band prided itself on playing -- and playing well -- several hundred rock 'n' roll classics without any serious rehearsal time, and the two would try to outdo themselves by coming up with obscure tunes -- on stage.

"In the studio, though," Kennedy says, "John's a very subtle player. Besides always being in tune, playing in perfect time, being a fast learner, he also brings a remarkable sensitivity to any musical situation. And he's terrific in a number of areas too -- singing, playing bass, producing."

Jennings fans are not shy about saying they are almost to the point of despair that he has not stepped forward as a frontman, never recorded even a local album of his tunes, not pursued a major label deal. He has recorded demos, but at what might be best described as a pokey and cautious pace.

"It's a survival reaction," he explains. "I want to do things right. The music business can eat you up before you know it. It's coming, though."

He has just finished producing the tracks for Mary Chapin Carpenter's first album, and he says he now plans to spend some time on his own demo project soon.

"Really," he says. "Soon."