Waitaminute. That sounds like the sound chip in the GBA is more related to the FM synth one in the previous GB models than what I thought it was using, which was a programmable wavetable chip similar to the SPC700 DSP chip used in the SNES.
If this thing's only capable of doing FM synth at best, with only two programmable channels, then how the heck would we expect to port the OST to GBA and not lose nearly all sound quality?!
Note, now, that the only experience I've had with a GBA (or its sound capabilities at that) is not much, I've never actually played one, and the ones I have heard in earshot, had soundtracks that leaned toward NES style (read: FM synth) than SNES style, yet I keep hearing that the specs claim the SPU is better than that, so I'm confused.