I'd like to keep it below $200USD but I use them so much that I'd probably consider going up to 300 or 400 if the pair is right

I'm looking for a nice set of headphones to use while I'm working. I work in an office cubicle and currently use a Audio-Technica QuietPoint ATH-ANC7 set. My biggest goal is to be able to listen to my music (reasonably-)loud without everyone around me complaining that they can hear it (as is the...