Have had a bunch of Headphones in my life (Focal, Sennheiser HD 6xx, AKG 240 and 271 and many others) and had settled on Beyerdynamic dt770pro for vocals and dt880pro for guitars. Yesterday I took the plunge on a higher level one and got the dt1990pro. What of a difference! The level of detail and definition is a huge step up, the Soundstage is lot broader and deeper and the bass (it's an open back) are absolutely impressive. I've ended up lowering the level on the headphones because it doesn't need that much volume to hear all the details.
The guitar sounds and effects really shines and feels a lot more complex and dynamic.
They aren't cheap, but well worth the price.