Take 6 has been spreading its harmonious musical gospel for two decades.

The a cappella group's signature sound has won them various accolades including Grammy Awards and Christian music's Doves.

Northwest Indiana and Chicago fans will experience the group's meticulous close harmonies firsthand when Take 6 performs Sunday at Horseshoe Casino's The Venue in Hammond.

Through the years, the sextet has never abandoned its gospel roots and continues to entertain audiences with a rich collection of spiritual favorites and other tunes.

"We sing what we believe in," said Take 6 founder and member Claude V. McKnight III. "Interestingly enough, in 20 years of doing this, it's been apparent to us that anything you try to do that your heart isn't into, you find out you don't do as well."

Along with McKnight, the group also stars Mark Kibble, Dr. Cedric Dent, David Thomas, Alvin Chea and Joey Kibble.

McKnight said there have "certainly been opportunities" to exclusively go the commercial/secular route in music but they always chose not to do it.

"The strongest thing that we do is gospel and/or spiritually based songs," McKnight said. The group has showcased its jazz vocal foundation in many projects, however, including the latest album "The Standard."

Although the songs on the album are considered jazz and pop standards, McKnight said they were "carefully" chosen.

"All the songs are considered spiritually sound. This is the kind of music we always subscribe to do," he said.

If the tunes aren't "straight up" gospel, McKnight said they're inspirational or "good news" promoting in some way.

On "The Standard," listeners will find classics such as "A-Tisket, A-Tasket," "Sweet Georgia Brown," "Someone To Watch Over Me," and "Straighten Up and Fly Right." Among musical artists appearing on "The Standard" with the sextet are Aaron Neville, George Benson and Al Jarreau.

Concertgoers will likely hear a fair amount of the album's selections as well as other Take 6 favorites "Destiny," "A Quiet Place," and "Spread Love."

McKnight said, in concert, they strive to make it fun for the audience.

"It's important for us to involve them. We get them to sing from where they are," he said. "And we want to make sure when they leave the show, they say 'Wow, I didn't realize that was just all vocals.'"

A cappella tunes aren't often great commercial favorites but McKnight believes there'll always be a demand for strong harmonies in the industry.

"The human voice will never go out of style. We're not a radio-friendly group and never really have been but we've been able to sustain a career for 20-plus years," he said.

McKnight, a Brooklyn, N.Y. native, was always attracted to music.

"My extended family was very musical and I started singing in the church choir," he said.

When he was 5 years old he'd accompany his mother to choir rehearsals and ended up enjoying it.

"My grandfather was the choir director. So I couldn't get away from music," he said, laughing.