Adding a Turntable Mat

   I have an older turntable (Pioneer PL-530). Am the original owner. Have done a few things to keep this table operating as original as possible. Yeah, I know this isn't a high end table by any means. Rather than receiving a flood of advice on what tables are better, I would like to hear from someone who may have knowledge/experience with different types of table mats.
   My table has no VTA adjustment capability. The stock platter mat is rubber. Seeking minor/inexpensive tweaks and if a different mat may or may not provide any perceptible improvement. If it's inexpensive and provides no improvement....no problem.
   Here's my question.....For example...If I installed a thin cork mat, could that mat simply be placed on top of the existing rubber mat or should the rubber mat be removed first and then just use the cork mat? Remember, this table doesn't have VTA adjustment.
Thanks