John, there seems to be a break in the action at the moment, so I'll again raise a point about room size and power requirements. There seems to be an exaggerated concern about "filling the room" whenever it's bigger than average, and thoughts go to 500 watt amps. Room size and listener distance are certainly both factors, but sometimes the inverse square law is misapplied and a 6dB drop per doubling of distance is applied as if it was the only determinant. As has been pointed out before, the reverberent field becomes equal to the direct sound field at a relatively short distance(3-4')in typical-sized listening rooms(see the discussion and especially
fig. 10.4.1 here , with the result that the drop in total sound pressure level with distance is far less than the 6dB per doubling figure. Linkwitz also has a very interesting discussion on
room acoustics (especially scroll down to reverberation distance and amplifier power sections)which indicates why, as a practical matter, the more ordinary power levels that we use are fine for doing the job.
