This is from the Audyssey website FAQ section:

The MultEQ algorithms require acoustical information from multiple locations within the listening area in order to create the appropriate room correction filters for each loudspeaker and subwoofer in the system. The first measurement is used to determine the distance and level of each speaker and it should be taken in the center-most position of the listening area. After that, it is recommended to take 6-8 more measurements throughout the listening area.

The order of the measurements after the first one does not matter
It is very important to avoid extreme positions including up against the back wall or too far outside angle spanned by the front Left and Right speakers. Taking measurements in these positions will cause MultEQ to make unnecessary adjustments
Measurements should be at ear height with some small vertical variation.

I don't know - I think that what I did is quite OK according to them...

TAM

Yes, Dr. Kyriakakis's comments there and following are that the exact distance isn't critical, and he mentions one and two foot variations.

A couple of answers down he states ref mic distances between positions:

'The exact distance is not critical. Somewhere between 2-3 ft (1 m) is what we recommend.'

That's basically what I did. I think that you could drive yourself crazy with this stuff & unwittingly get into the law of diminishing returns.

Anyway, its good enough for now...

TAM

Not sure exactly but you mean but with MCACC multi-point you move the microphone to different seating positions during the calibration.

Thanks. That's a new one on me. I'll have to check it out further.

Not sure if it's a new thing, I have an SC-67 so it might be new for Pioneer.

I bought an SC-67 from Amazon last week. Still waiting on delivery.

Cool, I ordered mine from Amazon as well. I got it at the end of November and so far I'm loving it.

I believe I have read somewhere that Mcacc has up to three mic positions.

That is correct.