• PyramidV-color
Playwrights: Colin Escott and Floyd Mutrux. At: Apollo Theater, 2540 N. Lincoln. Tickets: 773-935-6100;. www.apollochicago.com; $64.50-$80. Runs through: May 29 (at least)

Million Dollar Quartet is the Little Show That Could, chugging merrily along for 30 months in a commercial production at the Apollo Theater. Last April it leapt to Broadway, earning three Tony Award nominations and one win (by openly gay singer Levi Kreis). Meanwhile, it chugs on in Chicago. It’s “inspired by” the factual December 1956 jam session of Elvis Presley, Carl Perkins, Johnny Cash and Jerry Lee Lewis in the primitive studio of Sun Records in Memphis, Tenn., where each of the four cut his first hit.

I attended a late-afternoon holiday matinee. Everything onstage was just ducky but the nearly-sold-out audience was bizarre, split 50-50 between grandparents and grandchildren, with Granny/Gramps evidently trying to convince the young’uns that they were hip and rebellious 50 years ago. Alas, their kidneys couldn’t hold out for the 105-minute show, and dozens of codgers walked in and out of the intimate house to pee, crossing corners of the stage as the band played on. I’ve never witnessed anything like it.

At $80 top, it’s not an off-Loop bargain but you get an awful lot of musical bang for your bucks. Million Dollar Quartet has been well-maintained during its long run and the current strong cast is dead-on in physical and musical impersonations of the four great stars. It’s fiendishly difficult to find capable singer-actors who also can play musical instruments at a professional level and look/sound like the people they are portraying. Gabe Bowling plays Carl Perkins to a fare-thee-well and doubles as lead guitar with all the right chops. Lance Lipinsky dazzles as boogie-woogie piano man-gone-crazy Jerry Lee Lewis. Sturdy Sean Sullivan effectively underplays Cash, while David Lago captures Elvis’s spirit and moves, although not his height. (Elvis was six feet tall.) Kelly Lamont, as Elvis’ singing girlfriend, adds visual and vocal flash.

Of course, Million Dollar Quartet is ersatz history, and is honest when it says it’s “inspired by” the jam session. The raucous string of greatest hits the boys rattle off bears very little resemblance to the actual jam, which was heavy on gospel music, Bill Monroe songs and acoustic instruments. The jam is just an excuse for a jukebox musical with a thin storyline and a meaty dose of rockabilly history, courtesy of studio owner and producer Sam Phillips (played to tremendous effect by the personable Tim Decker), who serves up narration directly to the audience.

Be warned that Million Dollar Quartet is much, much louder and more jangly than the original artists ever sang these songs, and louder than necessary. Critics back then thought rock was the devil’s music or a Communist plot, but it’s easy to understand this show’s appeal today: It offers a goodtime dose of “roots” rock played at modern volume by faithful interpreters.