I've been to hell and back, but I wanted this to work, and by golly it works. Two YM2612 streams occur simultaneously. Play two VGM files at the same time, and you could have 10-12 FM channels instead of 5-6.
Here's what I'd like to see -- someone willing to take a song and make two VGM files out of it. Replace "YM2612_A.vgm" and "YM2612_B.vgm" with your own VGM files. These could be more complex FM songs. And it's always nice having 2 DAC's instead of 1.
There are things I'd like to see happen with this. Even if you're not going to create a greater-than-6 channel song, at least just give my little program a try for the heck of it.
BTW: Exit by pressing ESC!