Low damping factor but fast& high current SS amps?

It's very simple to add a resistor in series with the output of an amplifier with a high damping factor (a.k.a. low output impedance) to get whatever damping factor you desire. The resistor value can be calcuated by dividing the nominal speaker impedance by the target damping factor value. So if you wish to have a damping factor of two, and your loudspeakers have a nominal impedance of 8 ohms . . . then placing a 4-ohm resistor in series will acheive the desired result.

Most audiophile parts suppliers have an assortment of resistors of the proper value - a non-inductive wirewound type is ideal, and a power rating of 20-50 watts will be more than adequate for the overwhelming majority of domestic applications.

There is both some conceptual as well as terminological confusion here.

All this talk of damping factor without a single tip of the hat to the 'q' of the speaker.
Critically damped speakers...Q-0.707 need much less amplifier damping.
Hi Q speakers can benefit from higher amp damping factor, but only to a point

The total Q of the driver/enclosure together (which is the figure to which you're referring) is VERY much dependent on the source impedance the driver sees . . . in the Thiele/Small equations, this is reflected through the driver's electrical Q (Qes).

Generally, drivers with a high Qes (especially with a low resonant frequency Fs) are more suitable for sealed enclosures, which (again, speaking generally) tend to work better with amplifiers that have a low output impedance. On the flip side, if you're designing a reflex loudspeaker with a Q of 0.707, the cabinet volume needs to be larger, and the port tuning lower, to acheive this with a higher source impedance (that is, a lower damping-factor amp). So for a given loudspeaker, the total system Q goes up as the source impedance gets higher, usually causing a mid-bass peak.

I'm of the opinion that the subjective sound of this mid-bass peak is the true source of the term "damping factor" for an amplifier, not for the literal mechanical damping of the woofer cone itself, or especially "damping" in the sense of classical Control Theory. Also, this peak can be frequently tamed by increasing absorption losses in the cabinet . . . that is, to add "damping material" (to offset the lack of "damping factor").

Comfortable or not, it is wrong. EMF is voltage. It is not voltage that damps the motion, it is a magnetic field.

I think that a frequent point of confusion is between the acronyms EMF (electromotive force), EMI (electromagnetic interference), and EMP (electromagnetic pulse) . . . the error is in assuming that "speaker back EMF" refers to "electromagnetic force" . . . which if these terms are used precisely, it doesn't.