Michael, my suggestion is that for calibrating the levels and distances of your speakers the auto setup provision of your 3805 is likely to be as least as accurate as could be done by manually calibrating with a separate meter. It shouldn't be assumed that any difference between the two methods would be in favor of the manual calibration; in particular a "wrong" measurement by the receiver of the sub's distance is likely to be more accurate than the physical distance shown by a tape measure, since a delay in the sub amplifier's processing will make the sound arrive later than the actual distance would indicate.
The room equalization processing is more controversial than the calibration and there are those who highly praise a resulting improvement, while others report that the sound was worse. Experiment on your own to form your opinion of your particular situation.
