Right now I need closed headphones for actual professional monitoring needs. Not to sit home to enjoy music, rather, think of this as "mission critical". So the requirements are simple: As flat and as detailed as possible, all while remaining durable for outdoor (sometimes sheer wilderness) uses.
Source device is a Sony PCM-D50, unamped.
Budget: Below $250 USD. I have the Sennheiser HD215 right now and I'm getting the feeling that they're no longer proper for what I need. Maybe ATH-M40fs? They claim a "flat response". Or the Sony MDR-7506?
Thank you very much.