I found a locked safe hidden at the back of a closet in my new house

Moving into the house we just bought, I found to my delight a mysterious locked safe at the back of a closet. I've asked a few people how to get into it, and the consensus is either to use powerful microphones to listen in on the tumblers (apparently stethoscopes don't really cut it) or to see if the hinges are weakened by time and can be removed by force without damaging the door or the mechanisms.

Before I get cracking, though, what do you think? I asked the previous owners for the code, but they don't know. They just assumed it was empty. It's a Yale safe.

I know that it's probably full of air, but you never know.