Terry9; when you mention both recessed areas, are you referring to the label and the record lip? If so, the manufacturer is to be commended.
As for your comment about aftermarket mats, I've also found that to be true, but not universally. Some platter mats can noticeably improve the sound of some platters; it depends on the materials and what you're trying to improve. For example, with a metal alloy platter I was able to greatly reduce background surface noise, improve bass control, and increase perceived dynammics using an aftermarket mat. But the same platter mat used on a platter made of an acrylic and vinyl laminate only dulled the sound. I also use a platter mat on an acrylic platter but the improvements aren't as noticeable as with the metal alloy platter.
And as for the Herbie's Donut, it's not the typical platter mat; it's a very thin (0.5mm and 0.8mm thicknesses available) elastomer "donut" that is essentially neutral. I use it to adjust for different record thicknesses so that changes in tonearm height (and thus SRA) are kept to a minimum. If there is a change in performance caused by the mat, it's not discernable by me. It does however, noticeably improve the sound caused by incorrect SRA. The Donut helps to maintain SRA between thick 180g-200g pressings and thinner 110g-140g pressings. If your tonearm height can be easily adjusted then the Donut isn't necessary.
Regards,
Tom
