Break in time for Sennheiser HD-600?

I've put about 30 hours on my new pair so far. Can anyone share their experience of how long I can expect break in to take?
My experience has been 50 hours to begin to hear the true sonic character of the HD-600's; 100 hours to finish the job. (This is assuming that all your other gear is already broken in.) An after-market cable, like the Stefan Equinox or Cardas, will really bring out the best from these fine cans.
I began to notice a difference after a couple of days of constant run in. I put my cd player on repeat & went to work, and even on the first night ( or after the first several hours of constant play) I noticed I had more bottom end and a deeper "soundstage".