In my experience, anywhere from 20 to 50 hours is pretty typical. That said, unless they don't sound all that good out of the box, it is certainly not necessary to run them unattended for hours at a time. Just listen to your music and enjoy. But if you want to burn them in by running them unattended for hours at a time, then yes, Little Dot recommends that headphones should always be attached when the amp is in use. I use a $5 pair of IEMs when running the amp unattended.
7/4/15 at 10:22am