I'm looking for some open headphones under or around 300$. I listen to many different genres, so as long as they are fairly flexible, it should be ok. I've found Sennheiser HD 598, 600, and also Beyerdynamic DT 880,990. I don't have an amp yet, but i will probably buy one. Do you guys have any suggestions for the headphones? as well as headphone+amp combos.