Amplification is a physical process requiring power input. The only way I can envision software having any effect (and it is a stretch!) is if the software allows higher input into audio amplifier OR lessens something limiting the power output of the audio amplifier. And even if you increase power input as a means to increase output, other factors come into play -- such as distortion, power dissipation in amplifier, etc.
You have any software that will allow my water pump to double the water output? Same idea...
Options: Replace audio processor (card?) or send audio to external amplifier.
Just plug it into a Marshall - preferably one that goes to 11!
Seriously though, is it a particular sound file that isn't loud enough or is it audio in general? The former may be fixed with some audio editing tools like Audacity or the Levelator (or any number of programs), the latter could be fixed with some quality powered speakers. (or a Marshall. Its hard to go wrong with a Marshall. Can you tell my latest Musician's Friend catalog came in?)