Beyerdynamic should be releasing the DT1770 pretty soon, I think it's gonna be replacing the DT770 closed-back can. Not gonna be cheap but I've heard that treble has been toned down a tad, with improved bass and, oh yeah, it'd be using Tesla 2.0 drivers. I personally think it look badass and can't wait for reviews. Been waiting for a good closed-back can to add to my collection, was considering the Shure 1540, but glad I'd waited......this is one can I'm so looking forward to.
Meanwhile, I'm really enjoying the Gustard H10, it brought out the performance of my Alpha Dog and HE500, especially the HE500. I'd actually considered selling the HE500 since I prefer the HE400i over it (using the Lyr + iFi iDSD Nano stack). The Gustard H10 amp and X12 DAC really made the HE500 sing.....better resolve, nice bass in quantity and quality, sick clarity and transparency. The H10 has very, very nice synergy with the HE500......never thought an amp would change my opinion of a can, but the H10 has made my HE500 the go to can in my collection. Next to it, the HE400i pales in comparison, losing to the HE500 in just about everything other than bass.