Greeting Mr. Hook-up,
I hope all is good on your end of the world.
In reference to your posting.
The ideal approach would be to have a multi-channel amp to drive each room with it's own amplification, leaving the Niles controls at 1X.
Now you could use a 2 channel amp to drive that many pairs, but there are aspects you have to be aware of, when you set the IM selection on the Niles controls to 16X, in looking at the chart provided in the manual you will see that it is assuming that you have all 8 Ohm speakers, and I say all because it is based on the global presentation to the amplifier. This also implies that you have an amplifier stable at 4 Ohms. Now when you are trying to determine the wattage required, this is where you need to know the efficiency of the speakers installed. Here is an example: using rough numbers, lets say you spec a 100 watt amp with 4 pairs of speakers and they are all identical speakers, right off the top, using a autoformer based impedance matching device you stand to loose 7-10% of power off the top, now you are powering 4 pairs with 90 watts. divided by four and each speaker pair is getting roughly 23 watts, now if you spec'ed a speaker that has a rating of 50-100 watts, the crossover is not going to get adiquate power to sound the way the speaker manufacturer designed it.
With that being said, I assume that you have Niles speakers installed so this problem won't figure into the equasion since Niles designs their speakers with these intentions in mind.
Jeff, I hope this answers your question.