Yes, as Nick and Fred point out, any reference to sufficient amplifier output levels has to logically mean clean and transparent, certainly not accompanied by "painful distortion".
Nick, one point to note is that the 6dB per doubling of distance factor only applies under anechoic conditions. In home listening rooms reinforcement from room surfaces is such that a typical result(as reported in research by Dr. Toole and others)is a 3dB loss per doubling. This is the factor which I apply in calculations relating to the sufficiency of amplification at safe listening levels. The typical result with receivers having ratings anywhere in the 100-150 watt area is sufficient output(clean!!!)with speakers of average sensitivity, such as Axioms, for those levels at typical home listening distances.
