I think Holm has a short webpage at www.holmaudio.com
And Eric...if you only have the afternoon to spend, you'll probably end up having to skip Holm (or make that your only stop)...they're about a 45 minute drive from downtown. The Little Guys are also far from downtown. Evanston can be quite a ride too. Where are you going to be specifically?
If you're downtown, you're near: Audio Consultants (Gold Coast store...on Wells St?), Paul Heath (on Clark St, in Lincoln Park), Pro Musica (on Clark St. in Lincoln Park), Avant Garde (on Clark St in Lincoln Park), and the Sony Store (for SACD...on Michigan Ave)
If you're near Evanston: Audio Consultants (on Davis in Evanston), Celestial Sound in Evanston?? (I'm not familiar with them), Quintessence (on Dempster St. in Morton Grove), Van L. Speakerworks (appr. 5600 N. Western Ave in Chicago), and Audio Image (appr. 5800 Lincoln Ave in Chicago).
There are plenty more in the various suburbs. Let us know where you'll be and we can be more helpful.