Correct. With no mat, there is a 2 mm gap between the platter and vinyl so no vinyl touches the platter (excluding label).
I think it sounds very good (not sure what it would sound like directly on the platter); however, I do not find the ring clamp does much to even out slight to sever warps.
I think it sounds very good (not sure what it would sound like directly on the platter); however, I do not find the ring clamp does much to even out slight to sever warps.