I suspect that the limiting factor here may not the the power output of your sound card but in fact is the tiny (and tinny) laptop speakers – assuming that you are using these to listen to.
If you are using externally powered stand alone computer speakers, then they ought to take a line feed from the laptop sound card and they have their own mains powered amplification circuitry built in. That ought to give you a fair amount of volume.
As a last resort you should be able to take a line out feed from your sound card and connect that to the line in on an external mains amp and from there to conventional speakers. You can burst your eardrums with that set up if you want to.