Theoretical and practical investigations in the optimization of microphone setup for 3/2-Stereo are presented. The “Image Assistant”, an Internet-application for calculating and evaluating an arbitrary L-(C)-R microphone setup is introduced. L-C-R main microphone configurations were compared in listening tests revealing differences in directional imaging, sound color and focus. Additionally, different room microphone configurations were compared regarding spaciousness and envelopment. Excerpts from the test objects are presented to demonstrate the existing differences.