The third run of the show - featuring Sara Bareilles, Ben Folds and Shawn Stockman as judges - will crown its new winner in a live episode airing Monday, November 28 at 8/7c on NBC.
When asked what he hoped to accomplish by the end of the season on a recent conference call, producer Gallen said: "I really hope that we've made some type of impression on the audience. We're now three seasons into it and obviously this was our biggest season because we were on every week for the fall schedule and that kind of thing.
"I really feel like we've proven ourselves as far as a viable music series that could be on the air for many, many seasons to come."
Gallen also praised the level of talent among the groups who have participated and said the greatest thing for him would be watching the winner enjoy a successful career.
"The most satisfying thing for me would be if whoever our champion is could actually have some success and find an audience and sell some records and get some great iTunes exposure, things like that," he said.
Gallen added: "I think that, to me, is when we really feel like we've accomplished our mission, because that really is what it's all about - finding this talent and figuring out who's going to be the best of the best, and will the audience want to go out and see them in concert and listen to their music beyond The Sing-Off.
"I really hope that this season will be that season where that happens."
Pentatonix, Urban Method and Dartmouth Aires will battle for the Sony Music recording contract and $200,000 (£129,247) prize on Monday's live finale.
The Sing-Off will crown its winner tonight (November 28) at 8/7c on NBC
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> Read Digital Spy's full Sing-Off headlines
Watch a promo for the finale below: