just wondering how to boost the volume of headphones louder on AUDYA4

it seems the overall volume on headphones is way, way soft, even at when main is MAX, and all parts are all way up,

on my XD3, if i put it full blast, it is VERY LOUD, almost unbearable...
on the AUDYA 4, at full blast, it's just, comfortable (in a quiet environment)

i need it much louder,
thanks to anyone that can help