An affectionate tingle hung in the air. High fives and hugs abounded. Sitting at my table in the cozy Cabaret Jazz at the Smith Center for the Performing Arts, I wondered: Do all these people know each other?

It turns out they do. They perform together in the top Vegas shows—Phantom-The Las Vegas Spectacular, Mystère and all the rest. Once a month, these accomplished performers gather to present original music. Vegas’ best musical brains, in other words, are busy writing lyrics and composing songs in their downtime.

An insider’s event if ever there was one, the Composers Showcase is the brainchild of Keith Thompson, the conductor of Jersey Boys, and Michael Brennan, conductor of Le Rêve. Six years ago, it launched at now-defunct Suede restaurant with free admission and word-of-mouth publicity. From there it moved to the Liberace Museum, where it stayed until that facility closed in 2010.

The Smith Center debut on May 16 signaled a new phase of public outreach, but the smallish venue ensures the monthly event keeps its intimate, what’s-going-to-happen-next excitement and charm. Almost every performer had the music in hand—these were not off-book performances—and used “my friend” when introducing the band, as in “my dear friend” singing backup, “my good friend” on drums. The human relationships that sustain top professionals in the industry were the real stars here.

Impresario Keith Thompson performed his song “On With the Show” before keeping up a witty repartee between a dozen acts. I roared with laughter at “Voice Lesson Number One” written by Mark Wherry, listened spellbound to Tyler Williams’ jazz band and felt my jaw drop when special guest Clint Holmes sang scat. Privy to these original songs across genres—from musical theater to pop, classical to jazz—I almost felt like a musical insider, too.