Damping factor has been misunderstood by many, mostly that the bigger the damping factor the better. Technically that is not the truth.
The optimal goal is to be "critically damped" which means you reach 0 amplitude fastest with no residual oscillations. Over damped which is many amplifiers on the market will have a slower time to 0 amplitude but will have no oscillations. Under damped is when you reach 0 amplitude fastest BUT there is a continuing oscillation for a period of time.
Not all speakers are the same obviously but they all will have a resonance down in the bass region. This shows itself as a large impedance spike on an impedance vs frequency plot. An amp with a huge damping factor will dampen this resonance without residual oscillation but it is not necessarily best because the time to get the motor to actually stop (0 amplitude) will be slightly longer than when it is critically damped. Over damped is without a doubt better than under damped but to critically damp is tougher to achieve. A good way to get best speaker to amplifier relationship is to have an adjustable damping control not so popular today. This control is to be able to dial in the best control over this nasty bass resonance. Typically current feedback is used from the speaker that allows both positive and negative feedback adjustment. Yes I said positive feedback (negative resistance) which is how you can actually achieve better damping with a tube amp vs SS amp. BUT this can be implemented to SS amps too so the technology is not mutually exclusive.
Many tube amps I have tried will have what I call one note bass, this is that resonance frequency being louder than other frequencies and mistaken as "good bass". Another HUGE issue with tube amps is the fact that the output transformer core does not have enough flux to be able to maintain the low frequency waveform, this shows itself at the trailing edge of the waveform where it falls apart. This non-linearity rears it's head as second harmonic distortion which will reinforce the fundamental frequency as extra information. Hifi we really do not want extra information (distortion) that wasn't present in the original program material. So this extra information/distortion sounds like enhanced bass or "good bass" but it is really just distortion. Not saying this is good or bad, I am saying it accounts for many claiming great bass from tube amps.
I would like to see more offerings from manufacturers of amplifiers with a damping control to allow the user to dial in the best control between amplifier and speaker. You do not need a huge DF, anything over a DF of 8 is useless and what you really need is an adjustment to critically dampen the nasty bass resonance present in almost all speakers.
