Senn 600 break in time?

Hello All,

Long time no posts.
Anyways, I recently got a pair of Sennheiser 600's from a friend.
He had them for over 3 years but only ever put 10-15 hours on them.
I was wondering how many hours hours it will take to break them in.

My Grado 225's took over 250 hours. They did not really start sounding good until over 100 hours. It was not until the very end were it all came together.

Just wondering what people opinions is with the Senn 600's.

Thanks,
Nick