We say :
The range and quality of headphones available is huge! Moving up from the entry-level PreSonus HD7 headphones, these newly released PreSonus HD9 headphones are a great intermediate option with super sound isolation through their closed-back design.
PreSonus say :
When you need to do serious work without bothering anyone in your living space and without being distracted by outside sound, choose PreSonus® HD9 headphones. They're clean-sounding, extra-comfortable, and offer a broad, transparent frequency response that ensures accurate mixing.