Wrong DA?

I have this DA: FREE SHIPPING — Ingersoll Rand Dual Action Air Sander — 6in. Dia, 4 CFM, 10,000 RPM, Model# 311A | Air Sanders| Northern Tool + Equipment but it isn't really doing much. I think it is a finishing DA. I am stripping panels for epoxy using 80 grit.

I have read about using 36-40 but I am worried that is too aggressive.

I have a electric die grinder and a air angle grinder.

Should I get a different DA or stripping discs for the die grinder or angle grinder? The die grinder isn't speed adjustable.