Damping factor can be significant in system performance, but sometimes is over-emphasized. Some time ago sushi pointed out the falsity of the claim of "tighter bass" supposedly provided by some solid state amps with very high damping factors. I concurred and referenced speaker designer Dick Pierce's findings on the point. That article now appears in expanded form
here in Audioholics. Note the insignificant effect on damping at bass resonance shown in the first table until damping factor is in the low single digits. The separate matter of response fluctuations due to speaker impedance fluctuations is shown in the second table(columns 3 and 4 reversed)and is of more significance than damping at bass resonance, but wouldn't appear to be of audible significance at the frequency points involved until at least a damping factor under 20.
The conclusion is that Mr. Russell's suggestion of speaker wire resistance of not more than 5% of nominal speaker impedance(i.e. equivalent to a damping factor of 20 if receiver output impedance was zero)is reasonable and allows sufficient damping factor when combined with typical solid state amps having output impedance of less than 0.1 ohm. Of course in some worst-case situations involving high amp output impedances of several ohms(e.g. many tube amps), that in itself is sufficient to cause audible inaccuracies.
