Originally Posted by FBinNY

I never know how much the OP knows or has done prior to posting, so forgive the following question.

You describe "metal crunching/grinding" when using the outer 1/3rd of the cassette. Any chance we're talking about simple chain/front derailleur cage rub?

Otherwise, consider chain plate rub on the chain ring teeth, with lack of lube, or maybe a bit of grit. Simple test here, add some oil to your chain and see if the nature of the sound changes.