It depends on the speakers, some sound even better by way of there own settings. Others actually sound worse because there eq settings work good on speakers, but bad on headphones.
Your best bet is to just give it a try. Or use the front headphone jack if you have one on that PC.
I do not have those speakers to test with, but it should be a quick test. i do not think it will be exactly the same as plugging into the sound card.