You have to balance your equipment.
What good is a soundcard if your speakers can't support its potential?
How good is your speaker?
Don't know much. Their sound is quite much excellent I think, you can see a photo of them:
Depending on the implementation - the onboard sound card would cost somewhere around $10 - $30 if bought separately. So buying another sound card that equal the performance or even with 20 percent gain of the onboard sound card is a waste, in my opinion.
Yes, tha gain will be 20 percent only I think. I thought buying an extra card will save the MOBO from the load.