Well, I am into electronics, so I searched the CMI8738 datasheet in Google, and I saw that it had an embedded OPL3 synthesizer to provide compatibility with legacy hardware and software. Interesting. Of course, the Windows 7 driver didn't allowed me to enable or use it, neither the one for Windows XP did it. I tried downloading that DosBox version that has inpout32 and allows you to use a hardware OPL3, in case the FM synthesizer was enabled by default, but it didn't work. Damn...
Later, while reading all the datasheet in order to figure out why my the card made my computer reboot every time I tried to shut it down (it turned out to be a nasty design error in the sound card PCB), I saw that the card has a flag called "FM_EN" (FM enable). I coded a small program using inpout32 that allowed me to peek and poke registers in the processor's I/O bus, and tried manually setting that flag to 1. The result?

Well, the result is that I got a sound card with a very good OPL3 implementation running in a 64-bit version of Windows 7

The SoundBlaster isn't working, because I haven't figured out how to enable it.
Here's a recording I made using DosBox and AMusic playing AN_OTDSE.AMD https://docs.google.com/file/d/0B1Hl-pa ... sp=sharing