I don't have the realtek software as I have an m9700 with the soundmax setup.
There should be an option in the realtek software though to show the full equalizer and be able to adjust seperate frequencies. I lowered the frequencies I mentioned above, and the rattle/static sound stopped on big bass sounds.
Here's something I found online about a realtek equalizer, not sure if it's the one you have. You have to turn on the equalizer though to be able to use it.
Here's what it says with that pic...
"When you click the Sound Effect button, a window opens that allows you to select the Environment and the Equalizer settings. You can select an Environment such as Under Water or Auditorium. To use the Equalizer, click the Power button in the center of the circular equalizer control to turn on the Equalizer. You can click a preset button, such as Pop or Live, or manually adjust the settings and then save them for easy selection later."
The one in the m9750 should be similar.