The man was in Las Vegas for a convention, and found himself with a free evening. Nirvana! What choices! But our man saw it as no choice at all.

Armed with a national directory, he called the local chapter president. He was quickly invited to the weekly rehearsal. Two minutes after he arrived, he was handling the tenor harmony line of "California, Here I Come." He had more fun, the man said, than he ever has, or could, at a roulette table.

Barbershop singers are like that. It is no accident that one of their oldest standbys is "Let the Rest of the World Go By." Barbershoppers will launch into their hobby whenever, wherever. As Mike Wallen put it last Friday night, the kick is "the overtones, the enthusiasm in those overtones. Nothing rings a room like they do."

Ironic that he would say that, for just as he did, the room was ringing with a more familiar sound.

Applause.

Baritone Wallen and three confederates from Alexandria had just placed fourth in this year's barbershop quartet contest for the southern division of the Mid-Atlantic district. They thus won the right to compete at the district finals this fall. Although the scene was the auditorium of Stonewall Jackson High School in Manassas, it could have been a winning sports locker room.

Wellwishers pumped Wallen's hand. Fans asked how he had done it. He and his songmates kept saying that they mustn't be smug, that the big test still lay ahead. The only thing missing was some announcer with perfect hair shoving a microphone into Wallen's face.

But perhaps that was fitting, too, for barbershoppers may be the last artists of the modern age not to depend on electronics. When they sing, the only aid they allow themselves is one soft toot on a pitchpipe. The foursome hums once, to "find" the first note. Then off they go - without remixing machines, rhythm guitars, tapes or replays.

But if barbershop harmony can warm one's toes, barbershop lyrics can furrow one's brow.

Going back to dear old Dixie, getting a thrill when Susie simply walks down the street, returning to mom and dad if the world gets to be too much - life just ain't that simple, folks.

But that is precisely the point. The lyrics are a throwback to the Gay '90s, when barbershopping was invented, and to the Not-So-Gay '30s, when barbershopping became popular anew. It's nostalgia music, without the guile or cynicism that the music of the '70s thumps at so incessantly.

And barbershopping is catching on in Washington. Catching on to, ahem, beat the band.

According to Donald Vienne, president of the Mid-Atlantic District of the Society for the Preservation and Encouragement of Barber Shop Quartet Singing in America, nearly 700 people a year are joining the society in the states for New York to Virginia. Only 400 are dropping out. "We are a growth industry," Vienne said, "even though a great many people don't know barbershopping exists."

Friday night's contest pitted 20 Washington-area quartets against one another. The 80 singers ranged in occupation from Smithsonian Institution geologist to Army private. But very few in the audience of 400 knew who was who, or cared.

"When we get together, we get together to sing," said Terry Lee Jordan, publicity director for the southern division of the Mid-Atlantic district. "You can know a guy for years and not know what he does."

Perhaps more remarkably, barbershoppers have not come before the crosshairs of the women's movement. They are all and always men. While there is a women's barbershopping society called the Sweet Adelines, it is an acknowledged offshoot. The real thing is tenor, lead, baritone and bass. None wears a skirt.

"It's got to be that way," explained Mike Miller, a Montgomery County SPEBSQSA official. "Men and women are endowed with different vocal capabilities. Women might be able to 'get' the tenor notes, but not any of the others."

Some women don't get barbershopping, period.In barbershop lore, it is neither rare nor unexpected for a singer to arrive at rehearsal one week and sadly hand in his uniform. For the umpteenth time, a wife has said that it's either her or the music.

"The average quartet rehearses a minimum of eight hours a week," said Bill Taylor, a baritone from Alexandria. Add to that at least one night a week of chorus practice, and blend in the fact that wives and girl friends are always observers, and it is little surprise.

A big surprise, however, is how well some quartets can do without years of getting used to one another.

Mike Wallen's group, Tags and Swipes Forever, made it through Friday's contest even though they have sung as a group for less than a month. The other qualifier from the Washington area, Winning Hand of Arlington, has been a unit for less than two years, a paltry history in rock, classical or folk music.

But competitive success is always secondary to just plain fun. Groups have sung for years without winning a blessed thing. "It's for fun, ego, showmanship - the ham in us," said Jordan.

Indeed. For at that very moment, four middle-aged gents were on stage in red flannel suits and white flannel derby hats. "If all my dreams were made of gold," they sang, smooth as bourbon, "I'd buy the nworld for yoooooooou."

No one could hate that. Not even the cynics of the '70s.