Gramovox, which makes the players, has assembled The Gramovox Holiday Choir, an iPad-powered ensemble that plays one song for one dollar. All of the money goes to the Greater Chicago Food Depository.

“The concept that one dollar equals one meal really resonated with us and we wanted to create a new, interactive way for people to donate to a great cause,” says Pavan Bapu, co-founder and CEO of Gramovox.

The choir is located in the lobby on the south side of Merchandise Mart and will perform there through Friday.

Photos obtained from Gramovox.