We know that burning a metal with Duralumin burns away all of the metal in one burst. Does doing so with Feruchemically charged metal result in a more powerful Compounding, or just result in the power coming out all at once?
So I believe you're asking what happens if you're compounding a particular pair of metals and then also burn duralumin. The following words from Brandon should answer that:
Questioner What happens if you burn duralumin while Compounding?
Brandon Sanderson So, what duralumin does is it burns out of all of your metal in one burst. So it doesn't necessarily gain you power, it makes it all happen at the same time. The same thing would happen.