What makes a Stradivarius sound good?

Back in my violin days, I was graced with a lesson from a music PHD.

She had a Stradivarius on loan from a local university and I got to watch her play it.

Now, keep in mind that most high-quality violins have great sound. You get what you pay for.

In the hands of a master violinist (who could play Bach's Chaconne from memory) they all pretty much sound the same. It's difficult to tell the difference between a standard violin ($1,000 and up) and a strad in the hands of a master.

I'm sure they are wonderful instruments, but the average classical fan is not going to be armed with the aesthetic to understand the sound.

If you had audio equipment to measure the specific sonic profile of a Stradivarius, perhaps you could see the exact difference.

That's my entitled opinion. You expect a professional to have the highest-quality equipment.

So, what makes a Stradivarius sound so good? About 100,000 hours of practice.