Okay.. I've owned my HD570's for almost a year now. Till date, I've never done a break-in on them.
However, seeing that I've built my buffered-multiloop amp for them; I'd like to ask:
Would it do any good to try and break them in now?
Just basically cranking up the volume to quite above normal listening levels and leaving it to play overnight.
Currently, I can hear the music clearly when the headphones are about 60cm (2 feet) away from me. Is that loud enough? Or too loud?
Theoretically it is best to break in HP's using music or sound that covers the entire frequency range to fully exercise the drivers and loosen the mechanism up. However, normal listening does virtually the same thing over time. Lou is right you probably have them burned in by now and anything more you could do would not be apparant to your ears. In other words you are good to go.