Dean, as I've commented here before, the Crown discussion appears to somewhat nonsensically attempt to relate suggested amplifier capacity to the power handling ability of the speakers, e.g., 2 or 4 times might be suitable. This makes no sense because far less than the amount which the speakers can handle(which typically are in the hundreds of watts)might be actually used in typical home use(not the pro applications they emphasize).
The calculator there also doesn't seem to give realistic results. In Dr. Toole's book he cites studies indicating that in typical listening rooms the overall volume loss is about 3dB per doubling of distance. If we use a 91dB sensitivity number for the M80s, the loss at about 10' would be about 4dB, i.e., a level of about 87dB per watt. You want to use a 105dB peak, although I can assure you that few if any of even the most dynamic classical recordings have a dynamic peak 25dB above the average level. In a recent issue of my AES Journal, a group of CDs was analysed for dynamic range. The highest shown was about 18dB and what was rather amusing was a very uniformly loud rock item which had a dynamic range of essentially zero.
Be that as it may, using the 87dB per watt number at 10', 100 watts on a peak having a duration of likely much less than a tenth of a second would allow for playing the peak at about 107dB.
