Bill MacKay here, music researcher at Chicago Artists Resource. I apologize for the late reply. After searching for some time, I must say it was hard to find much in the way of agents that seemed relevant. Though I know they are out there!
This website is said to be good. I have not had personal experience with it.
You can set up an account and advertise your duo, etc there.
If I can find anything else, I will let you know ok. It may be helpful to contact some of the faculty at the area universities such as University of Chicago, Roosevelt, Columbia College Chicago, DePaul, Loyola
and such schools-music centers as:
Piano Forte http://www.pianofortefoundation.org/
New Music School http://newmusicschool.com/contact/
I hope this is somehow useful, and best of luck. By the way, you also mentioned a pop group. I did not include those as a general search for agents in Chicago will usually bring up a lot. So I tried to focus on what seems harder to find. Take care, and let me know how it's going.
all the best in your music and projects,