I don't care how good the sound is when I'm in ideal listening conditions, if I'm pissed from having a headache and bleeding ears for 10 hours it won't matter

Overall, there are some ergonomic bumps with these, but the sound is well-suited for critical listening

As I'm not an expert I can't speak to whether or not these are "Flat" - but they have drastically improved daily listening.

This mix I put on a thumb drive to test in my favorite listening environment, my car

The HD 660 S is incredible