I'd build a Windows 98 VM in my Mac with VirtualBox to run some old games, like "Z". It is running, but without the great soundtrack. When testing, I realize that the soundtrack is in midi files, and not even Media Player is playing any midi. It opens the file, knows time etc. (recognize the file) but no sound is played.
There is a Sound Blaster Midi Sinth installed, the problem might be the VM itself that don't emulate the full Sound Blaster 16 card. I'm thinking about some alternatives: to change the VM sound card (not a clue of how to do it), or to install a driver that synthesizes the midi in wave to use the wave port that is working, but didn't find one.
Also couldn't get in the Virtual Box forum, I'd make an Oracle profile, but didn't work. So here I am… any ideas?
The standard MIDI port is 440, make sure your software is configured correctly to use the card (though judging by your level of knowledge in asking I'd imagine you've done this).
While this isn't specifically an answer about making VirtualBox do what you want, I'd recommend DOSBox when doing DOS or Win3x gaming over a regular virtual machine for performance and emulation accuracy.
You can get any DOS-based Windows (including 95) running on DOSBox or at least one of the patched builds of it (I recommend Taewoong's build at http://ykhwong.x-y.net/ as it is the most feature-complete). You could probably make 98, 98SE, and ME run on DOSBox too, but anything that won't run on 95 can probably be made to run on a modern version of Windows with less trouble.