Thanks again for your tips!
To be honest, I think I still have to hear my HD650 to their full potentials, since they didn't blow my mind yet. Don't get me wrong, I already think they are a really good pair of headphones, but since I actually hear to many different genres, I don't think it does a great job with that, since the area where it really shines is mostly the midrange (vocals are really intimate indeed and kinda magical), but bass is really lacking as well as soundstage, imaging and the overall definition is not the best. That's why I felt in love with the DT1990, I heard almost all Beyerdynamics and even if I think - of course - the T1 2nd gen is the best one so far, I don't think they are twice better than the 1990 - as its price suggests. They shares the same new Tesla driver at the end as well as other sound characteristics. When I heard the T1/1990 for the first time (coming from the HD650) it was like I was listening my albums for the first time, since there were a lot I was actually missing with the Sennheiser. And the really good thing with the 1990 is that they perform well with almost all kind of genres, whereas other headphones (like the HD650) outperforms only in a few areas (like vocals), plus the 1990 got a really neutral and linear sound with a slight warm touch (like the HD600, but again, with more details, soundstage and bass - that's why it has become my reference headphone). But, at the same time, that's also the point of having different types of headphones. And that's the main reason why I've always choosen to buy less expensive headphones, instead of only 1/2 flagships. Infact I also like to experience different sound signatures and use the best headphone according to the genre I wanna listen to. And that's also the reason why it's quite a bit I was thinking on buying a tube amp, since changing tubes will allow me to experience different sound signature within the same amp. And that's kinda cool!
By the way, going back to the amps, if you say that the DV kills the LD mk2 at the end, I guess I will just wait a bit more and buy the Darkvoice. I was just wondering if I will enjoy it also with other headphones and not only with the HD 650 (even if you and other people say that combo is really good, if not the best).
About the 6sn7, didn't you say before it's actually possible to use on the LD mk2 as well (using adapters)? And, if yes, do you think the sound is still better on the DV?