A/V Processor question: Pre-amp out vs speaker out

Will the A/V Processor audio set-up and speaker balancing including Audyssey operation work OK if: as opposed to using all channels on the speaker outputs or all channels using pre-amp out to a 5.1 or 7.1 amp; will these features work if I use the preamp out to the Front Left & Right only and hook up the center and surrounds to the speaker outputs? (I realize that the preamp out is used for a powered subwoofer in any case).

Thanks for any input on this question.