The most obvious improvement I've made using demagnetization has been the Walker Talisman. I bought it not knowing how effective it is at the speaker terminals, just waving it back and forth for 5 to 10 seconds. That really opened up my system. My friends purchased it just for that reason after hearing what it did to mine (and theirs now). Prior to every listening session. My friends also recommended waving it over (one pass only needed) speaker cables, power cables and ICs. Yes, I most notice it over the speaker cables, despite mine having incredible shielding. Must work on the exterior static. I barely notice the difference when waving it in front of my speaker drivers as recommended. Back the terminals-wow!!!
I switched from using the Talisman to the Furutech Destat III. It eliminates static from the plastic and vinyl when the latter are held in one's hand (not on the platter). There is a definitive Youtube showing why and how.
I did not hear much if any difference using the original Furutech CD demagnetizer previously mentioned.