I am copying Doug Schroeder's discussion on "Damping Factor" from his Dagogo Gold Note PA-1175 Mk II amplifier review.
Doug's findings with respect to this amp are, I believe, of significant importance and of critical value. For this reason, I am sharing it in it's entirety. The link to the review follows at the bottom of this post.
From Page 2 of
@douglas_schroeder 's review:
"My enthusiasm for the amp was dampened slightly but became a white-hot flame of interest once I began to work with the unusual Damping Factor feature. I can put up with the quirks largely because of two things, the uncanny ability of Italians to get the Midrange perfect, and the “best of both worlds” experience the PA-1175 offers through use of the DF switch.
In the current amplifier market Gold Note may have the coolest feature available in the Damping Factor. This is no gimmick or marketing ploy, but a serious uncommon advantage conferred upon the owner. Anyone who has spent time with solid state versus tube amplifiers knows the variance in sound can be dramatic. Speakers react substantially differently when hooked up to a solid-state amp with high power versus a tube amp with lower power. For our objectivist friends reading this, I have no desire to debate my perspective with you.
Why am I discussing power when the Damping Factor is all about controlling the excursion of the drivers? For the simple reason that the DF feature alters the sound in such a way that one senses they have switched out the amp from a higher power SS design to a lower power tube design. That is how much the DF control changes the listening event. I have placed enough heavy monoblock class A or A/B amps with my speakers, and also enough heavy tube amps with those same speakers. to know the effect immediately. The DF operates in a fashion that gets similar adjustments to the sound as if had I physically moved two separate amps in and out of the system.
As an aside, on this topic we see the proclamations of specifications-driven audiophiles shown to be wrong by the reality of performance. I have seen dismissals of Damping Factor as irrelevant to amplifier operation, or at a minimum much less important than current delivery or wattage. It takes about ten seconds hearing the distinction to know that Damping Factor has a major effect upon a speaker, and while it is not typically treated as seriously by the hobbyist as those other design considerations, it should be. Once I heard the effect of switchable DF, I began paying very careful attention to that specification.
Gold note recommends “…use of the low DF (25) setting with high sensitivity speakers and mini-monitors as the amount of energy used to reproduce the lower range of frequencies usually suits these kind of speakers best… Bigger or mid/low sensitivity speakers perform better when driven by a higher power amp with a higher DF.” While I agree in general with that guidance, there are a couple of things to consider, one being the overall quality of the speaker. Some speakers are not terribly precise, regardless of the advertising that claims otherwise. I would tend to run such speakers with the higher DF in order to tighten them up, and I would turn to cabling to tune them in terms of tonality.
Conversely, a speaker with such beautiful expression as the just reviewed VanL Speakerworks Silhouette is a treat to hear with either of the DF settings. The Silhouette is a purist’s speaker, a refreshing departure from the crass offerings without the signs of a master craftsman’s touch. It is a minimalist speaker design, as is evidenced in the supreme quality of the 6/5” wooden cone dual motor mid/bass driver and minimal crossover, and as such lets the alternative settings of the PA-1175 be expressed readily with deftness. The Silhouette is not designed to be bone crunching, but soul caressing. See my article for a thorough introduction to this rare gem.
The other consideration is that there is no telling what the preference of the listener will be. Some people enjoy a fuller, less tight low end. Some people prefer a sharper, laser guided upper end. Others insist on a predominant midrange that draws attention away from both the upper and lower end, even to the point of suggesting anything lower than 40 Hz is unnecessary for acceptable recreation of the event. For that reason it is worth trying the DF setting in both positions regardless of the speakers you are running. As the PA-1175 is robust, and the power structure is not affected by it, you should not enter into a situation where a speaker will be underpowered by going to the low DF setting."
https://www.dagogo.com/gold-note-pa-1175-mkii-solid-state-stereo-amplifier-review/
