Now is where the fun stuff comes in.
Before we start probing modules. We need to learn a few commands.
The first one is "lsmod" This lists all current modules loaded, you can do it at any time to see all modules currently loaded.
The second command is "rmmod" This removes (unloads) a loaded module.
The last one is "modprobe" This is a high-level way to load modules, it checks dependencies (relieving you of this task) and tries tries to load the module and any modules it depends on, in a sane matter.
One very important thing about modules are their dependencies. For example, a lot of sound cards/chips etc are AC 97 complaint. So let's say my ESS Allegro is AC 97 complaint. Well, when I "modprobe essallegro" it will load the ESS Allegro, but it depends on the ac_97 module as well, so that will also be loaded.
The only reason I say this is because when doing an "lsmod" you may see more modules than you actually modprobed, this is because the depended modules are being loaded as well. If a module doesn't work, you can just rmmod it and try again.
You said your card was an OPL3saX, let's start with OPL3sa.o.tgz
$ modprobe OPL3sa
Notice I did not use .o or the .tgz, when loading modules you just nix the extensions, as a matter of fact they will not work with the extensions.
If you get a lot of garbage when you try to modprobe, chances are something is not right. In this case, just "lsmod" and "rmmod" the modules that may or may not have been loaded (sometimes they will load even if they don't work).
Go down the line until one works (doesn't spit a whole bunch of text at you).
How do actually know it works? Well, most modules mount themselves on the device /dev/mixer Actually I haven't ever seen anything else. Other possibilities, depending on kernel version and distro are /dev/dsp /dev/sound But I have never run into these.
Back to the game, when you get one that "seems" to work try and play some audio (I use command line mp3 players like mpg321) A nice command line mixer is rexima. You may or may not have it.
Hopefully that works for you. Sorry for the length, let me know if you have any more questions or problems. I am going to go get something to eat...
-Weaver