There is no way to do this. I will explain the process to you, a sound card sends out information to your speakers in the same way a cd player reads a cd and send information to an amplifier. Computer speakers are self powered so have their own amplifier inside them. This is what boosts the signal. To get a louder sound you want better speakers to get a clearer sound (this doesnt neccarily means less distortion) you want a better sound card. The soultion that i can think of if you didnt want to buy better speakers is to try a phono pre-amp this will take the signal from your computer, as longs as its analogue which it will be and re-organise it and strengthen it. a good hi-fi retailer so not an electrical store should be able to get you one. with the headphone situation your sound card powers your speakers so you just need a pre-amp booster type device they should make one. i've been in the home entertainment design industry for a few years off and on, leave it with me and i can see what products are available.