Hmm that's interesting. I did not see that happen when I used a nad amp with my marantz nr series as both a power amp as well as integrated. As long as the mic hears the pink noise, it should not matter whether the speakers are directly connected or via a Poweramp. Could it be audyssey version dependent?
One more slight point of contention is that, I kept the speaker cables plugged in to Marantz as well as Vidar Power amp ; I alternatively plugged the Cable into speakers depending upon the Amp being assessed by Audessey. Since Marantz did recognize the front speakers correctly when connected via Vidar, the chances of speaker cables plugged in on AVR side shouldn't have resulted in absence of dynamic IQ and Audessey for front speakers. Next time I'll check it out with unplugging Speaker Cables from AVR side as well.
@sunand777 yes its the most powerful AVR I've used, but it isn't harmful to check out all the options available and share the experience with FMs so it might be useful for everyone. Since I didn't have a budget for a worthy preamp to go with Vidar I was checking out with the preamps I already had. One of the best SQ was with a cheap 6j1 Chinese tube preamp (with Jan 5654W tubes instead of stock) and Vidar combination until I got a Schiit SYS.