under File > Import options you can find the formats studio supports. Iges is pretty standard for cad nurbs data. Step is becoming more prevalent; it works better than iges sometimes, sometimes worse.
dxf sucks unless you’re working with polygons or 2d lines only. but for poly i use stl or obj. you can use iges for poly if you want.
granite from pro/e works too, acis works nicely for solidworks, if you have one of the direct connect products from alias you can exchange directly with unigraphics or catia or sdrc i-deas.
most of these formats pass basic or no surface material info, and none include lights, cameras, transforms, dimensioning, history, etc.
subd from maya or other package needs to become nurbs before studio will accept it. point cloud and section data are acceptable as iges, but you need surfacestudio or autostudio to do something real work with those entities.