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.

[1] https://en-us.sennheiser.com/high-quality-headphones-around-...

[2]https://www.schiit.com/products/magni-1

[3]https://drop.com/buy/massdrop-sennheiser-hd6xx

[4]https://drop.com/buy/massdrop-x-sennheiser-hd-58x-jubilee-he...