Just one question, Roy, did you record the sounds from your output?
If yes, you definitely should rethink about getting a soundcard. I just did a scan of my spectrum, chosing a B24, engines are idle. This is the spectrum I get on my machine.
As you can easily see the strong sounds are well below 100Hz, the very same area your onboardchip simply cuts out.
Anyway, I even more understand peoples argument about crappy sound, looking at your spectrum and I can just hope some people invest some 20 bucks to get a soundcard with hardware sound-acceleration and a headset/set of boxes, that can display them.