The only MIDI devices Anvil of Dawn support is those that follow the General MIDI standard... The MT-32 does not do that, it is technically impossible for it to follow the GM standard.

But that's as it currently stands. What I'm curious about is whether it would utilize the MT-32 if it was modified so the MIDI was piped through channels 2-10. That is to say, I'm wondering whether it only supports GM because someone slipped up when coding it(i.e. is it a bug?), or whether they just deliberately put an incompatible sound system in the setup options list for whatever reason.

MT-32 is made before General Midi standard. It is still the same MIDI data stream out from your PC, but the MT-32 just has different instrument mapping that is not compatible with General Midi standard.

It is possible to take in MT-32 compatible midi stream and change the instrument mappings according to closest match in GM standard, and it is just as simple to do the mapping from GM to MT-32. But the hard part just is if the GM tune just uses more channels than MT-32 is capable of, or a similar sounding instrument just does not exist.

Staticblast wrote:

..... or whether they just deliberately put an incompatible sound system in the setup options list for whatever reason.

This is what they have done and other games does this aswell... for example most Bethesda games wich also has GM support claim false MT-32 support.
I don't know why the setup/installation programs even mention MT-32, maybe the sound programmers though MT-32 was GM compatible?

And since the MT-32 has such lo-fi sound quality so can you actually listen to several GM soundtracks using it without it sounds "too" bad.

The reason for the confusion is most likely that Miles Design's AIL 2.0 sound system --- that's the one with *.ADV sound drivers and *.XMI song files --- had no driver for "General MIDI with MPU-401 interface". All their General MIDI games (except one) would use the MT32MPU.ADV but supply it with General MIDI instead of Roland MT-32 song data. This works well enough, except that MT32MPU.ADV still sends out MT-32 system exclusive messages to the General MIDI sound source. (I noticed this when I tried to implement a feature to automatically detect whether MPU-401 MIDI data should be interpreted as MT-32 or General MIDI data.) I suppose that is where this idea got started.