My recollection is that while some PC sound cards of the era technically supported arbitrary FM and/or wavetable synthesis, it was difficult or impossible to ge

My recollection is that while some PC sound cards of the era technically supported arbitrary FM and/or wavetable synthesis, it was difficult or impossible to get any custom sounds out of the MIDI side of them. I remember there typically being the General MIDI sound set, and maybe some custom presets on the higher-end cards. The big exception I ran into was the Yamaha DB50XG, which had an unbelievable (for the era/price) synthesis engine, but I had to buy third-party software to customize the instruments. I heard stories that implied vaguely similar things about the Gravis Ultrasound, but never owned one myself.