There are very few headphones that contain the sound completely. Usually when you hear a mini-disco from across the room, despite them using closed headphone, it's because someone is listening at ear-bleeding volumes.
Better to just turn the volume down and enjoy the music for many more years instead of going deaf at 30.
Also the 429 has a mostly balanced sound with a noticeable but tasteful bass emphasis which is enjoyable for low listening volumes.
