The PC version supported PC Speaker, AdLib, Roland MT-32, Sound Blaster, Pro Audio Spectrum, PS/1 Audio Card, General MIDI, Thunderboard, CDA Tracks and Disney Sound Source.
King's Quest 6 Full Soundtrack
The date I have for working on KQ6 was July, 1992, with an October release. It was the first one that -I- worked on where I wrote music "GM first" and mapped to MT32. LB2 was done in early 1992 and was written for MT32 and mapped to GM at runtime, but I believe that both games shipped with support for both devices. If we did our job right, the user would not know which device was written to. I have no info on Island of Dr. Brain... Rob could be right about the shipping support and his design focus.
We composers wanted to work on the nicest sound equipment we could have. I remember we were told that marketing data showed the vast majority of our customers were hearing the audio on an Adlib or SoundBlaster 2-op FM card, and that we should be writing to _that_ device first. But, that was a difficult sell. At my subsequent job I worked with the Sega Genesis and, listening to the Sonic2 music, learned what masters of FM synthesis could accomplish. Even then, with 4 operators, Sega's authoring system, and a single chip focus, I could never get close to what Masato Nakamura did on that game. He had some magic I didn't have access to.