It can be tough to break out of New York's underground music scene, but some performers want to stay there.

Dozens of performers rocked, serenaded, grooved and moved judges at a try out Tuesday to land coveted spots in the MTA Arts for Transit's Music Under New York program, which held its 27th annual audition at Vanderbilt Hall in Grand Central Terminal.

An eclectic group of 61 performers were scheduled to perform in front of a 31-judge panel -- a mix of musicians, art professions and MTA officials -- vying for about 20 slots for Music Under New York, which has roughly 300 active performers this year.

"The quality this year is over-the-top," said Sandra Bloodworth, the MTA Arts for Transit director and a judge. "It's going to be very difficult."

The judges, who will pick winners in the coming weeks, heard solo musicians who played the guitar, ukulele, viola and didgeridoo; and acts that performed music from around the world, from placed such as West Africa, Cuba and China. People who gathered to see the auditions heard an acoustic version of Pharrell's hit "Happy," Beethoven's "Fur Elise" on guitar, and a cover of "Man of Constant Sorrow," popularized in the movie, "O' Brother Where Art Thou," among other recognizable tunes.

"There's such a rich tradition," Meagan Gillis, a 25-year-old xylophonist from Annapolis, Maryland, said about subway busking. "When people have a case of the Mondays I feel like this would raise people's spirits."

Anyone is allowed to perform on a platform in front of an empty instrument case or hat, as long as they follow transit rules and don't block people from getting around a station. But there were performers auditioning who said they preferred to join Music Under New York to avoid any issues with MTA staff or the NYPD.

"It's better to have a permit to play here," said Luca Spanio, 31, of Venice, Italy, the frontman for the rock opera act, Venetian. "We have less troubles with police."

Joey Johnson, a 29-year-old Upper West Sider who raps and dances as J.J. Biotic, said he had recently started to put on small performances in the subway system.

"People really loved my lyrics and my outfits," said Johnson, who performed with purple hair and a flamboyantly colored outfit. "I'm a wild character."

If he lands the audition, Johnson said he hopes to be discovered by producers.

"To have Music Under New York behind me really allows that message to shine for all of New York to experience and give a starving artist a chance to really shine for the public."

One of the judges, David Spelman, who founded the New York Guitar Festival in 1999, said he thinks about what he would want to listen to while traveling through the subway when considering the performances.

"[I am] just trying to think about what would enhance, make the commuting experience more vibrant and enjoyable," Spelman said. "I ride the subways too."

A commuter from Mahwah, New Jersey, 57-year-old Jerry Mayo, said subway performers in New York City sound great, recalling a Delta blues duo who sounded like a professional in a club.

"They need an audience," he said of the performers. For the riding public, the music "fills a void. It's kind of a symbiotic relationship."