Beyerdynamic T1 Set- up

Hello,


I am looking on buying the headphones mentioned in the title.

First of all, I would be interested if it' s worth seeking the T1 2nd generation, over the 1st one (detachable cable is a plus, but the graphic is quite close for both versions) .
Second, is the T1' s built before 2010 have problems with the treble? What are the SN' s from which they fixed it?
Third, I have a HK970. Would it be enough to supply it, or should I search a dedicated one? If so, which one? Budget is not unlimited, unfortunately.


Thanks!