Contestants who successfully passed the open audition perform a chosen solo song in front of the panel of six producers and further trimmed down to 32 (or 36 in season 3).

The panel makes the final decision based on the vocal range of each contestant and the members' ability to work together as a team.

The very last round of the final stage features a much larger studio audience and is televised live.

The final ranking is determined by combining the votes of the celebrity panel, live audience and the other quartets not performing.

The overall MVP is decided among the winning teams based on the most number of collective votes from the live audience and celebrity panel.

Each of the 36 participants select the three songs they want to perform and the production team groups them according to their choices and vocal range.

Note: This show airs on a cable channel/pay TV which normally has a relatively smaller audience compared to free-to-air TV/public broadcasters (KBS, SBS, MBC & EBS).

The show has been credited with reintroducing the classical crossover genre to the South Korean public and popularizing it.

[23] It also increased interest and awareness of the bel canto style of singing more commonly used in classical repertoire, especially opera.

[24][25] The unique format of the show, where both amateur singers of different backgrounds and trained singers were randomly grouped together and given the artistic freedom to arrange and design their own performances, ensured that the performances showcased songs from a variety of genres, rather than only traditional classical crossover.

[26][27][28] The JoongAng Ilbo, noted in an op-ed on the ratings success of the first season, positive reception from viewers and the high quality of the performances: "It was also the moment when unknown musicians who had excellent skills but did not have a stage to sing to their heart's content were reborn as stars.

"[29] The Korea Herald praised its focus on the contestants' musical skills and professional training and their preparation process prior to each performance rather than overly relying on the "entertainment factor" and "personal storylines" characteristic of most K-pop or idol-focused domestic audition or survival programs.

[30] Viewers have praised the choice of "producers" (the six-member panel) as they were selected based on industry experience and expertise, rather appearing merely to boost viewership.

[32][33][23][34][35] The show gained notoriety within the domestic classical music community due to the large number of classically trained singers and voice majors participating as contestants and the presence of opera singer Son Hye-soo in the panel of producers.

Seasons 2 and 3 notably featured contestants who had been winners or finalists at prestigious vocal music competitions abroad, held postgraduate degrees in voice or were already establishing themselves at various opera houses in Europe.

[41] Such attitudes persisted into the 2000s, with tenor Park In-soo being infamously expelled from his opera company after collaborating with folk singer Lee Dong-won for the 1989 hit "Nostalgia" (향수) while musical theater veteran and crossover singer Kai, a voice major from Seoul National University and the first crossover recording artist to top the domestic classical chart and chart in the top 30 of the Gaon Album Chart, faced considerable opposition from most of his professors when he shunned a career in opera.

[42][40] The classically trained members of the winning teams from all three seasons have openly stated that the restrictive environment was what prompted them to audition for Phantom Singer rather than pursue a career solely in opera and classical music and welcomed the program as a much-needed platform to boost the profile of the crossover genre.

While crossover vocal groups have existed prior to Phantom Singer, the quartets formed on the show continue to enjoy much more mainstream popularity and regularly appear on weekly televised music programs such as Open Concert and Immortal Songs: Singing the Legend.

According to statistics compiled by the Korea Performing Arts Box Office Information System (KOPIS), concerts by Phantom Singer participants dominated ticket sales within the "classical and opera" category for the first half of 2021, despite COVID-19 restrictions.