Those Rega arms can't be adjusted for platter thickness....I don't use any mat at all which to me sounds the best (VPI turntable). Go to Amazon, etc. buy all platter mats that you can return and test them all in your system.
Platter mats for a Rega Planar 2
Back when I worked at an authorized Audioquest dealer and when AQ made a Sorbothane platter mat, I compared that product to the stock Rega felt mat and came away with the opinion that the Sorbo mat was noticeable better sonically.
The thing is, the Sorbothane mat is a huge PITA to use... it sticks to the LPs and holds on to dust like a champ, it can even damage LPS if they're forgotten and left on the mat for too long (yeah, don't even ask, at least it was a fairly expendable record).
While it's fairly straight forward to clean, getting it off the glass platter and re-centering it once dry, is also a PITA.
Have any of you other glass platter equipped Planar owners found mats that perform as well as Sorbothane (or better)? I'd love to replace the AQ mat with something that has the same lively and solid sound, but doesn't come with the maintenance issues cause by a sticky polymer.
As far as what's been on it in the past, the OEM black felt was the next best of what I had tried, with the two that I have clear memory of being the Discwasher felt mat and the very dense/dead polymer mat from Onkyo's 1990s flagship TT. The Discwasher was not quite as good as the Rega mat, but close, while the Onkyo mat sounded flat, muffled and lacked bass clarity ...legit terrible!
TIA!