The mat I like best is

[Trackside]

The stock rubber one! I've tried various combinations of cork, wool, leather and 'achromat' and even a double achromat ( including bonding these with petroleum jelly) and each time the rubber next to the vinyl sounds more open, natural and real to my ears. For VTA reasons with my Sumiko headshell + 3mm spacer and DL-103 I can't run the rubber mat on it's own so it always needs something between it and the platter and it's now 4mm cork but having the achromat under the rubber also works but when I tap the platter with a knuckle (ouch) it doesn't sound as dead as with the cork. Even the rubber on it's own has a slight resonance so maybe some 'constrained layer damping' is happening with the combo of different materials.

[mj-mostly]

I use the stock rubber mat sandwiched between two home made cork mats. I found the treble to be a little harsh with the stock mat, so bought a sheet of cork from the local model shop, and made a mat. One cork mat on top the stock improved things, another below gave the sound I like. The treble is still extended, but is now smooth and not wearing out.

[Trackside]

I'll try the rubber / cork sandwich then - thanks for the tip!

[VinylIsTheBest]

I'm using a rubber mat from a Technics SL-B3 (which I had years ago) on my Thorens TD-160. Using the Technics mat turned over (record sits flatter & sounds better) on top of a very thin rubber shelving liner. Tried cork, acrylic etc., and found this sounds the best.

[scho2684]

For many years now I use the Sota mat (on the SL-1200)
It was back then one of the greatest "sound openers" for me
More open sound is a statement here!

Never tried anything else, because the Sota mat is fixed and can't be removed...
But in compair with the stock mat this was truly a big improvement.

A true recomendation, and not a very big investment on what is and remains a low-end table

[alanomt]

I take it that the mat the OP is referring to, is the stock SL1200/1210 Technics mat.

A very useful item, good quality and often available for peanuts as they are discarded from the box by the DJ users.

Not only do I use one on a SL1210, one is a good fit on a Fons CQ30.

I have recently re joined the Garrard 401 owners after a lapse of 40 years! The original Garrard mat had become very hard and luckily I had been given an unused Technics mat, with just a felt disc to infill the centre recess in the Garrard platter, the Technics proved a perfect fit.

Works for me.

Alan