Interesting observation about burn in....
I don't think I notice any major change of my K371 after using it for a while. Since nothing strange really stands out, my first impresion of it brand new vs well-used do not really change.
Same for hd560s. My first impression of it, vs about a month later, did not change.
But this one, at least when listening for the first few songs from brand new, have something really strange that stood out.
This is either second or third song I listened from brand new:
When brand new, the cymbals sounded really strange, very artificial, like unnatural high pitch noises only.
After a few hours using it, today is the forth day, the cymbals sounded more like what I used to get from my k371. So, burn in appears to happen to mine.....
Anyway, mine only comes with the black cable. No other cable came with it.