Most probably your onboard shows as realtec in device manager. If you download and install the latest drivers from the realtec site, you get the equilizer for free. Your mobo should also have a optical or coaxial digital audio output. Use that with the Edifier S730 and you can change the bass setting with the included remote control.
Only if you stay with the analog connection. That's why i recommend the digital connection. The speakers have there own "soundcard" (in fact it's a DA converter) and that should be optimized for the speakers.
Thanks for your help. I just have one more question. For this speakers I will be using an EU adapter. The speakers come from Germany and I will use them in the UK. I will turn off at night. Is this safe?