We are remodeling our kitchen. There is an existing laminate flooring installed over 1" particle board underlayment. Beneath the under layment is a plank subfloor 3/4" thick laid on diagonal with small gaps between boards.

We are planning to install hardwood flooring in its place. I plan on tearing out the laminate and the particle board underlayment. Throughout the rest of the house there is hardwood flooring installed directly upon the original plank subfloor.

My question is this. Do I need to put down any plywood on top of the original plank subfloor? If so, how thick? I've heard numerous viewpoints and am looking for clarificaton. Many thanks for your help.