PC Volume Isn't As Loud As Usual...?

Im using a computer I use in my workplace everyday with headphones like usual. Everyday I have the settings the same, so I cannot figure out why this could be happening. Anyways, I was wondering if there is software to boost the output of the volume. I know it is based on the power output by the Video Card installed and the decibel limit of the headphones. I am using different headphones today, but they are Apple iPod ear buds which I know have a way higher output than what they are giving. Any advice? Please dont tell me to check volume limits and balance... I've checked it all and am not very computer illiterate (: