You've got a great pre/pro there. Be sure to select "Stereo" rather than "Surr" (surround). This may seem like a flippant remark, but it really does make a difference in the sound stage, imaging, etcetera, even with only two speakers connected.
By speaker "configuration", in addition to distance settings and "large" or "small", etcetera, I assume you are including channel balance, which needs to be done with either a calibration disk such as AVIA, or the built-in pink noise test tones (which take at least 30 seconds to engage; not just pushing the "Test" button, but holding it down for about half a minute) in either case, using a sound pressure level meter. Of course, this is also important to achieve a realistic sound stage and correct placement of voices and instruments.
Enjoy!
Burke