Last time I heard about Rovin... was in the 60's I think. They are still around, huh. And Mat and Dave I never heard about.... small place?
Oh boy, now your in trouble
Matt from Matt and Dave's clay is Matt Katz, who moderated clay and glaze technical before you. They’ve only been around a few years, still working on expanding I presume.
Rovin opened in 1957 and is on its third set of owners. They've stayed fairly local.
I think they went out of business, unfortunately. http://www.mattanddavesclays.com/