however the Iron Audio acrylic platter does not have a LABEL recess machined into the top surface so if you do not use a mat of any sort, the record will not sit flush with the playing surface. Iron Audio recommends the use of a mat.bummer. The problem with going to another thinner mat is it may not provide adequate label relief. Other mats like the Sorbogel. Acromat, or Ringmat are thicker (I think) so will compound the problem. I recall seeing somewhere a replacement spindle for Regas that are longer to accommodate a a thick acrylic platter. I'm not sure where to find one or what they cost, but I would imagine they're pricey.
The options I see for you are 1) buy the extended spindle, or 2) scrap the IA acrylic platter in favor of a Funk Acroplat, or 3) try a thinner felt mat, or 4) live with the mat you have.
Personally, I would buy the funk acroplat.