As i said..i am only one and FIRST one having a headphone amp based on their NSL speaker amp..so he couldnt give me an exact number,,i am his guinie pig (my amp took so long as he tried new things on my amp he never did before). That amp (NSL) is said to take humongous amount of time to burn in... More then any other amp he made... He once told me that my amp needs around 6months user burnin time..thats about right..as i use my amp around 3-4 hrs a day since febr...and a quick calculation showed me it now has a burn in time of around 450hrs now... So 6months is about right..well as long the amp is improving i know its not burned in yet...last wednesday it soundsignature changed rather significally.... I hated eminem stuff (wav) on this amp a few months ago...sounded flat and the 'special effects' sounded fake..and the bass sounded fake also! but last wednesday my mouth fell on the floor when i heard 'his car' hitting the water, or the boot being slammed shut on same car (with his supposed girlfriend in it) on a certain track..So scary real!!! And Rain...as if ur feeling the rain....
And this all of a sudden!!! I also can listen to music on 21:00 oclock position now..until now i maxed out on 20:00 before it got to loud... Music is more liquid now..more real (dont know how to say it differently), especially on high quality live concerts with lots of instruments ....
Have to update my review about this..until now (after the first month ofcourse) the improvements were small..and to my ears only improved in soundstage and placement...
Damn... Cant wait to get it burned in completely... Hope to have my new custommade VENOM headphone cable and my two new custommade BC62 powercables also in august...and just got myself a new audio rack (present of my sweet ladies at home!) and some of the sexiest feet for under my amp components (check my profile for details..lolz) ..to show off the amp even more