I'm a Dummy, Tell Me About Turntable Mats

@astolfor PM me. I have an unused SPH Cu mat.

Thank you atmasphere, I think you said it better than I. 
Lew, I know of no hard data that says it is a definitive sonic problem. We both know it exists because we hear it directly. If we hear it the assumption would be the stylus does also. I apologize if I contradicted myself. But it is useful to define our terms so we all know what we are talking about. Record noise is what you hear in the background behind the music including dirt and scratches. Let us say that tracking noise is the noise generated directly by the stylus tracking the record which in all respects is just like that diaphragm in the Victrola. The mat has to dampen the resonance without reflecting it back. IMHO the record has to be held down tightly as the mat is not doing it's job if the record is partially in the air. I think the fact that disabling the vacuum increases tracking noise is telling. You use the Sota reflex clamp which performs the same function as long as you are using that washer over the spindle. Keep your amp off and listen to the tracking noise with and without the clamp. See if you get the same results I did. 

I think this is like what the Supreme Court justice said about pornography. To paraphrase, he said he couldn’t define it but he knew it when he saw it. I can’t define tracking noise but I know it when I hear it. Except I’m not even sure of that.

new sota mat has same impedance as the LP….. something Ralph can appreciate from an engineering perspective…

in general all mats / clamps are flavorizers…. approximate the record lathe cutter to disc to platter relationship and neutrality might be achieved…

however that doesn’t happed at lacquer test… Bob L uses a Brinkmann w special glass platter and a unique clamp…

what does R say….music not distortions.. ?

I have the utmost respect for Ralph of Atma-Sphere on most topics, but I do tend to disagree with him on vinyl playback. IIRC, Ralph thinks a top version of a Technics 1200 with stock arm is pretty much as high as one needs to go with a turntable. Contrast that with Harry Weisfeld who's made some more ambitious decks (admittedly I am no longer much of a VPI fan) and he advocates for no mat at all on his massive aluminum alloy platters, even with his relatively unstable unipivots! I have tried a ton of mats with my Reed 3P's and various high-end cartridges. On my aluminum with copper top Steve Dobbs platter on my 301 I have found that no mat is just as good if not better than any mat. Copper has good qualities of it's own which explains why some platter mats are copper. On the massive platter being used on my TD124 I have a carbon fiber mat that I have kept on for no particular reason-the same deck sounds just as good with no mat. I bet I have five other mats that no longer see any use at all from Merrill, Herbies, and others. 
I think of Malachai-the on-again and off-again apprentice of Mike Fremer who with his humble Pro-Ject deck has repeatedly exclaimed the value of his various mats. https://www.analogplanet.com/content/malachis-mat-mishegas-felt-mats-rega-pro-ject-and-audio-technic...
For. those that don't know basic Yiddish, "mishegas" means craziness. 
The idea that a record resonates due to a tiny stylus modulating in a groove and that said resonant vibrations feed back into the stylus as the stylus continues to trace further into the groove-further than the creation of the inciting grooves/vibrations-is just that-an idea. An unproven mental pre-conception. 
As I said before, mats will change the sound. The issue is whether they improve the sound and that is subjective and system dependent. In general a mat is going to somewhat deaden the sound, but by only a very slight degree. I have found-and this is just my humble opinion-that when a platter gets incredibly massive and is coupled with a somewhat "cushy" mat, record weight or clamp, and periphery ring, all these things will slow down the sound, turning it from lively to anything but. For maximum liveliness/dynamics/propulsive punch, go naked. Record right on platter, no other mishegas.