A scene in the second act of Warren Leight’s play Side Man illustrates the soul-transporting properties of music far better than words could. Jazz trumpeter Gene (Eddie Yaroch) plays an ancient recording of a long and fervent trumpet solo by a long-dead musician for his brass players. The far-away, almost ecstatic looks in the eyes of Gene and the others – heroin junkie Jonesy (Tom Hall), hopeful lothario Al (Don Pugh), and nerdy Ziggy (Scott Striegel) – tell all you need to know about these musicians.

These are side men (players who can solo or blend into a group with equal facility), and their medium is jazz.

But for all the joy she brings, the muse is also a demanding mistress, and this is a memory play about the side man named Gene and his failed attempt to serve two masters: music and his family. Leight knows his subject – his father Donald was a side man.

Gene’s son Clifford (Brian Mackey) narrates, the story, covering three decades between the 1950s and the ’80s as he chronicles the parallel stories of the rise and fall of side men and of is parents’ marriage – and the resulting collateral damage to their son.

The upstart Bang! Productions (founded by Scott Striegel and Michael McKeon) presents Side Man through Sunday, Oct. 11, at Diversionary Theatre. Striegel directs and acts; McKeon contributes a terrific set that allows the action to flow smoothly.

Gene won his wide-eyed young bride when he told her he was a side man for Frank Sinatra and promised to get her tickets. But years of Gene’s inattention and late hours took their toll and Terry (Amanda Cooley Davis), relegated to second place in Gene’s life, turned to the bottle for companionship.

Meanwhile, time and musical styles have passed these musicians by. Now their most frequent gig is to meet at the unemployment office and then repair to a nearby hash house where they drink, talk music and harass blowsy waitress Patsy (Jacque Wilke).

Clifford, caught between the need for connection, the family’s increasingly contentious home life and Terry’s alcoholism, may remind you of Tom Wingfield in The Glass Menagerie: Gene may be sporadically physically present, but he is every bit as absent as the elder Wingfield in the attributes that count: attentiveness and concern. As things at home careen out of control, Clifford is increasingly left to pick up the pieces as his escape possibilities recede into the background.

Leight parlayed the success of Side Man (winner of the 1999 Best Play Tony and shortlisted for the Pulitzer Prize) into a writing gig with “Law and Order: Criminal Intent” where, he notes sadly, “a few episodes can take care of you far better than a play can.”

It’s a loss for theater, because Leight has a facility for creating engaging characters that ring true. Try as you might to find villains or heroes in Side Men, you will only find imperfect people.

Striegel’s terrific cast serves the script well. The charming early connection made by Yaroch and Davis disintegrates almost too realistically into door slamming, shouting and avoidance, while Mackey breaks your heart as the kid caught in the middle.

Hall always lights up a stage, his portrayal of the addict Jonesy is no exception. Pugh’s attempted ladies’ man is a hoot with his fast talk and cheap rug, and Striegel’s Ziggy, with consistently slurred speech, rounds out the quartet with a believable interpretation. And Wilke is great as a sort of musical moll who has known almost all of them in the biblical sense.

“They played not for fame and certainly not for money. They played for each other,” Leight tells us. And in this bittersweet valentine to the days of side men, these actors do it beautifully. Don’t miss this wonderful production.

Bang! Productions’ production of Sideman plays through Sunday, Oct. 11, at the Diversionary Theatre. Shows Thursday at 7:30; Friday at 8 p.m.; Saturday a 4 and 8 p.m.; Sunday at 2 p.m. For tickets or more information, call 619-220-0097 or visit www.Diversionary.org.

“Tonight, you finally get what you paid for,” eight guys sing as they drop the towels they’ve come onstage in.

It’s the return of Naked Boys Singing!, a decade-old revue home again in West Hollywood, where it premiered in 1998. The surprise hit soon moved to Off-Broadway, where it is still running; since then the show has had more than 50 productions worldwide, and a filmed version was released in 2007.

Naked Boys Singing! plays through Sunday, Nov. 22, at Macha Theatre/Films, directed by Robert Schrock.

So what’s the big deal about eight guys in the buff? After the first few seconds, nothing, actually; they’re just guys singing some 16 songs about everything from the trials of being a nude maid to the mortification of getting hard in the shower after gym class to a nostalgic paean to the “beefy and soft” Robert Mitchum, “a perfect 10 back in the days of real men.”

These guys sing, dance, even do chorus line kicks, the splits and a slap ballet, all with a smile and those lovely birthday suits.

There’s no plot here, no social significance. Well, except perhaps “The Bliss of a Bris,” sung fully clothed: “They rave at the length/And the marvelous angle/They kvell at the girth/And they plotz at the dangle/ It doesn’t get better than this/The bliss of a bris.”

But mostly this is just a Chippendale chorus gleefully singing of “gratuitous nudity” in the opener and gay body image expectations in “Muscle Addiction” (“It’s true for you and it’s true for me/a gay man’s got to be fat-free”).

Many of the lyrics are clever, more than a few laugh-out-loud funny, but that’s not to say there’s no heart: there are two poignant ballads as well. Tony Melson’s “Kris, Look What You’ve Missed” is a love song for an AIDS victim, and in “Window to Window” two lonely men (Daniel Rivera and Victor Tang) flirt across facing apartment buildings.

The program lists 12 writers, which accounts for some variability in song quality. My favorites are Jack Harding’s jaunty “Perky Little Porn Star,” about a repressed Midwesterner who escapes into a new job (“I’m a perky little porn star from Skokie, Illinois”), and Eric B. Anthony’s show-stopping “The Entertainer,” a tribute to gay icons. This girl can kick!

Don’t bring your grandma from Orange County, or anyone who thinks Michelangelo’s David should be covered. But if you’re in the mood for 75 minutes of raucous fun, Naked Boys Singing is your ticket.

Naked Boys Singing! plays through Wednesday, Nov. 11, at the Macha Theatre in West Hollywood. Shows Thursday through Saturday at 8 p.m.; Sunday at 7 p.m.

For tickets or more information, call 323-960-4424 or visit www.Plays411.com/nakedboys.