So since matching Michael Gambon’s voice would probably be too difficult, I’m thinking of dubbing over both Dumbledores. The goal here is to make the voice consistent, and that would accomplish that. However, I doubt could pull off an old man voice. Maybe I can ask my brother, since he’s great with accents (I and others have told him he should try voice acting), but other than that, I have no one, so if anyone can do a convincing “wise old mentor” voice, feel free to contact me.