Headphones

I need advice on choosing closed-back headphones. For some time I was using ath-m50x. Overall they are ok, but there are some things about them I don't like:

1. On some songs there are sound in a certain frequency that are significantly louder than the overall scene. I think, the spike is in upper midrange, around 4kHz. I don't know if the problem is with my unit or all m50x have that problem, so my equalizer is always set to -4db on 4kHz, which affects all the upper midrange, making the sound odd.
2. The sound is "Close to the ears". There is too little space for the sound. On some complex songs, if there are many sounds of different frequencies played at the same time, they all mix together in a messy wall of sound.

I was at a hifi store and tried some headphones, and I really liked fostex t60rp, but they are semi-open, so other people can hear everything you are listening to. If you can recommend a good pair of closed-back headphones under 500$, please leave a comment.