I TRIED TO SUSS THIS ONE OUT WHEN YOU PREVIOUSLY HAD IT LISTED - NO LUCK! There is actually a band called Capital Sound in Illinois or thereabouts. I also tried en.wikipedia.org then searched Illinois Musical Groups which gives a lot of info. but I couldn't come up with anything. Of course, it may have nothing to do with Illinois!! 'll keep thinking.
Hi shaley, like Hazlinny, this one has been bugging me too. The only group I can find with those letters are M People. Capital could be the M in their name but they were a British group and I can't find a connection with Illinois.
The capital of Illinois is Springfield, and in Springfield, Homer, Barney, Chief Wiggum, Apu and Seymour Skinner all sang in a barbershop group whose name matches the 1,6 pattern - their hit song was called "Baby on Board" This should provide you with enough clues.......
Just noticed this has been solved and have to say "Congrats" too to Sequin. Previously someone had mentioned reference to the Simpsons and Springfield but it still didn't click!