The Vegas-based musical mimic opens his turn with a self-penned original tune, "For All the Stars," before he launches his comic rockets.

The first is a Johnny Mathis impression. Of course, Mathis' silky vibrato is one of the most impersonated of all voices. But Sorrentino plows new comedy fields by adding a twist: He hilariously points out that Mathis never enunciates consonants, and proves his point by singing vowels-only snippets of Mathis signatures.

But as clever as that is, the sequence merely sets the table for the subsequent brilliant, and howlingly funny, bit that features a series of Led Zeppelin songs performed by a zany roster of stars. This wonderfully twisted concept what-ifs, among others, Willie Nelson singing "Kashmir," Ethel Merman doing "Immigrant Song" and Jerry Lewis' Nutty Professor babbling his way through "Black Dog." The mere memory of this routine has me laughing out loud.

Beyond the Led Zep shtick, Sorrentino's best work comes at show's end with his clone-like Elton John tribute, which he has performed in Atlantic City as part of the "Legends in Concert" revue. Thanks to his stocky build, accurate costuming and sharp piano playing, the Sir Elton segment ends "Voices in My Head" on a note nearly as high as the one on which it begins.

What transpires between the early and late pieces is a mostly successful potpourri of celebrity impressions interspersed with video presentations, dance numbers by the 10-woman Sin City Dancers and occasional instrumental turns that allow the star to display his musical versatility.

The roster of artists paid tribute to (and gently mocked) by Sorrentino includes The Bee Gees, Frankie Valli, Luciano Pavarotti and Joe Cocker. Particularly effective is the bit that showcases Sorrentino's on-target takes of both Jim Morrison and Jose Feliciano doing their worlds-apart versions of the Doors' "Light My Fire."

Sorrentino also scores points for having the courage (if not necessarily the common sense) to perform "Hocus Pocus," a 1972 instrumental by the obscure Dutch rock band Focus. As he himself admitted, it's not a boffo piece among the bus-riding matinee audiences. However, it is one of the coolest things ever offered in a casino revue.

He also has some fun with mannequins during a Sonny & Cher bit, and offers video homages to the Marx Brothers and more contemporary comics.

Special mention goes to the 10-man Robert Sluys Orchestra, which provides Sorrentino with crackerjack support as the star navigates the show all over the musical map.

Tropicana has not had all that much success with its production shows the past year or so. Happily, "Voices in My Head" appears to have put the brakes on that trend.