Damping Factor and Overall Negative Feedback.

For completeness, I want to point out that Nelson Pass has posted some interesting articles on when low damping factor amps (i.e. high output impedance) are actually a good thing. I don’t have the links handy but I’m sure they are easy to Google.

He makes a very good argument for proper speaker/amp matching instead of always chasing for the highest damping factor.

Should add a little, that very low power, zero negative feedback amps tend to be the most colorful as the response curve rides the impedance curve of the speaker.   Colorful little liars!

Two different things, although sometimes talked about in the same sentence. 

Often we can improve the damping factor and reduce distortion by increasing negative feedback, but it's not the only way to achieve this. For instance, adding more output stages can also improve the damping factor without requiring more negative feedback.