A record 1,424 students applied this year, administrators said, but only 774 met academic criteria and were invited to audition.
Those students sat for a musical aptitude test, vocal audition, and, those with instruments performed prepared pieces.
Roughly one-third of the 774 students were auditioning for the 66 open slots in the fifth grade class.
Another third were auditioning for ninth grade openings which are few.
Another third were trying out for 6, 7, 8, 10, or 11 grades, when open spaces are usually minimal. Students were competing for spots on a wait list. This year, 225 students applied for entrance in those grades, which administrators said had no openings.
"I think it was an overwhelming amount of kids," said Kevina Chapolini, 49, after her daughter, Blake, emerged from her singing audition. "I was [nervous] because she was one of the first groups to go in so when people were coming out, I was like, 'Where's my kid, where's my kid?'"
But Blake, who auditioned for a slot in the ninth grade, came out beaming. She said she did well singing "Seasons of Love" from the musical Rent, and is hoping to go to the school to help her become an actress.
Because she applied to study voice, Blake took the vocal audition only. Instrumental applicants also take vocal auditions, teacher Vincent Rutland said, more for the purpose of evaluating placement if accepted than determining acceptance. Every student at the music school sings, the 52-year-old director of band programs said.
Rutland has learned over 13 years at the school to always expect a large applicant pool, as "we always have a strong interest."
Parents said they saw the school as not only a top choice but, in some cases, one of the only choices available to them.
"It would be nice if this school could accept more students," said Dawn Willis, 49, who lamented what she saw as a lack of good school options. "For the amount of taxes I'm paying, I think we should have a much better school system."
Willis was waiting for her daughter, Paige, to finish her violin audition, for which they had prepared extensively. Paige, a fourth grader, spends about five hours a week on the strings, Willis said, including private lessons and in-school lessons at the private Catholic school she attends.
If Paige is accepted to GAMP, Willis knows she will have to provide transportation for her.
The district has said the school will not have busing next year, principal Jack Carr said, and the school continues to plead its case.
Parents said Saturday they would do whatever it took to get their child to the school if accepted, including forming car pools and figuring out public transportation plans.
And while the large number of applicants means the school should still be able to fill its slots, Carr said, it's tough to see outside factors reduce an applicant pool that could have been even larger.
"I'm very proud, but I'm also somewhat frustrated," said Carr, who founded the school in 1974.
Contact Jonathan Lai at 856-779-3220, firstname.lastname@example.org, or on Twitter @elaijuh.