Mordy, at least 100 to 150 hours. When I first had my HD650 I hated the fit on my head. It was really tight. I could not wear them for long. I left them hanging on the box it came in when I'm not listening to them. After a few months, the tightness went away. It's now the most comfortable headphone in my stable. Even more comfortable than HD800. Who would have known that. T1 Gen 1 and HD650 are on opposite side of the spectrum. T1 is very revealing in the high frequencies. The mid range is more recessed compared to a HE560 but I love the tight impactful bass. With the HD650, you will notice the mids. It will have your attention. Lovely mids. Treble definitely seems loped off if you're coming from a T1. Bass, especially mid bass is full and blossomed compare to T1's bass. As much as I have a preference for details, I still like the HD650. On some genres like the blues, it's a headphone to strap on and just let the blues get to you. But.... if you ever get a ZMF Atticus, you will find the HD650 sitting on the headphone stand. That said, I need to get the LCD-2f back from my son. He's borrowed it too long. I want all my headphones with me when Ulysses comes home.