I currently own the Sennheiser hd 650's[1] with a Schiit amp[2] and absolutely love the combo. I also have them on a harman curve. You can get the HD 6xx from Massdrop for cheaper and it's the exact same driver[3]. My partner uses the Sennheiser 58x's[4] as well as she doesn't like to use an amp and they are probably the greatest bang for your buck I've come across.
Yeap... I went with Sennheiser 560S and I'm not pleased lol compared to the 7506 that I've been using for over a year. The 560S everything sounds blended.
Will give them a chance/listen for a bit. Just funny you get this obsession like "I gotta buy it" then disappointed.
Will keep it in mind I'll compare the 58x to DT 77 although open backs limit usage for me I think (not have other people hear my music).