Apart from the 16 channel aspect, some of which is just down to the way the general midi is played not because you need 16 simultaneous notes played at exactly the same time in all cases, it is very possible for Amiga to play back these tunes technically. DMCS was very early in the life of Amiga but around the time of the A1200 EA did release a sequel, although I doubt it has the general midi instruments available to play them without any hardware as you say.
Memory for holding the samples is the issue, but essentially things like Startracker and other 8-channel MOD players for Amigas prove that technically it is possible to do more or less the same thing, in fact MOD is a superior technology given you pick the samples anyway. After all what is a MOD player doing, the same thing more or less. 50mhz 030 is enough to play an MP3 on the fly so I see no reason why you need that kind of power to play general midi music files, I could convert that youtube video I linked to an MP3 and just play that back too then.
Anyway I need it as a MOD file for some other project, so looks like it's going to have to be a lot of manual experimentation and messing about trying to save out samples from other sources tacked onto a general MOD that exists already. Even so, the midi instruments are still not quite as good as the original ones, and I'm starting to wonder if there is a utility for ripping samples from MAME ROMs.....now that would be a really cool thing to do, and I think it is possible from some distant memory.
(I admit there may be some bespoke effects not supported but essentially trackers were doing the same things as a music player in Windows is doing now, sure the samples won't be in 16bit but really it's the same thing as comparing an IFF 256 colour image to a GIF file, it's all much of a muchness, and the technical requirements are too similar.)