For fresh or old veneer, I recommend Watco’s Teak Oil. (Sometimes I apply a little Howard’s Restor-A- Finish to the veneer before oiling it, just to bring out the grain and color a bit.) I don’t recommend putting wax atop the oil, as it collects dirt and it makes later re-oiling difficult.The opening on the back for the terminal panel is square on my “L300” cabinets, so that’s how I drew it. On later “L300 Summit” models (I am informed), it’s rectangular. I don’t have those dimensions.The stock terminal board is a crappy piece of Masonite. I suggest 3⁄4” MDF instead. My favorites are Parts Express part number 091-1142 (“Spring Loaded Speaker Terminal Nickel 13/16" Tab”); they look just like the old Pro-series JBLs but take much heavier cable and the holes go through.Note bene: Please do all your work at your own risk; I disclaim any liability for property damage or bodily injury.