Low damping factor but fast& high current SS amps?

"How does feedback lower DF"

Magfan – It increases DF (lowers output impedance).
Let’s take amplifier that has gain of 30 (31.6dB). When input voltage is 1V output voltage is 30V. Output voltage drops (for whatever reason) 1V under 1A load to 29V. That's 1ohm output impedance (DF=8).

Now, let's build this amp with gain of 300 but feed 3% of the output voltage back to the input in opposite phase. As a result amplifier’s output is the same 30V as before but input is the difference between 1V and 3% of 30V = 0.1V Let’s verify (1V-0.03*30V)*300=30V

Let’s load this amplifier with 1A. Our voltage drop inside is still 1V under 1A load, but output voltage will be higher than 29V because we subtract less from the input. Output voltage will be 29.9V and output impedance will be 0.1V/1A=0.1ohm (DF=80). Let’s verify. (1V-0.03*29.9V)*300-1Vdrop=29.9V.

Output impedance dropped 10 times. Expression 1+B*Aol is known as “Improvement Factor”. In our case B (“Feedback Factor”) = 0.03 (3%), Aol (“Open Loop Gain”) = 300 thus Improvement Factor = 1+0.03*300=10.

It is a little clumsy, but I didn’t want to bring whole feedback theory equations into simple example.

09-15-11: Kijanki
"So, I believe that high DF indirectly let's us know that the amp is trending towards high bandwidth (fast) & will be capable of high current delivery (if it's power supply is able & the music signal demands it)."

Damping factor and Slew Rate (speed) are not related.

Liquy - I never said they are related. That wasn't my quote.

Liguy,
that was my quote, just FYI.
as you correctly alluded: slew rate & bandwidth are related.
You also know that Q=i*t=V*C. so, V/t = I/C. So, slew rate can also be spec'd in terms of how much current into charging/discharging a capacitor.
Damping factor is an indirect measure of the amp's output impedance.
Needless to say, if an amp has higher output impedance (i.e. low DF) then it's more unlikely to supply higher current into the load (as most will be dissipated as heat).
So, there is a relationship between the two.

Negative feedback increases both DF and the bandwidth but it does not mean that high DF = fast amplifier. Amplifier might be slow to start with or have bandwidth intentionally limited at the input.

Slew rate might be important but let's see how much do we need. If music calls for 3V swing at 20kHz it corresponds to 3V*2pi*20kHz=376800V/s=0.38V/us and it is very slow.

It is hard to predict speed from DF. For instance Atmasphere S30 amplifier has extremely low DF=1 and extremely high slew rate of 600V/us.