I have the below two headphone amps and want to buy some new headphones that could pair nicely with both of them. http://tubes4hifi.com/HA14.htm (main amplifier) https://www.us.marantz.com/us/products/pages/productdetails.aspx catid=hificomponents&productid=hddac1 My budget is up to $500. Headphones I have used in the past are Grado SR125e, Sennheiser HD 650, and I currently have Hifiman HE400i's. The four options I am in-between are below: -Sennheiser HD 700 -Grado RS2e -Hifiman Sundara -Sennheiser HD 660 S The HA-14 currently has 6l6gc short bottle tubes and has a high and low gain. The Marantz also has a low/medium/high gain setting to work with. I have an all tube system and will mainly be listening to vinyl (classic rock, some metal, and some jazz). Any help and experience is appreciated!