NOTES: SoundFonts are an excellent source of free multisampled acoustic instruments. What is a SoundFont? A Beginner's Guide - Abyssmedia
The SC-55 was the "Reference Implementation" of General MIDI. Before the SC-55, MIDI files played differently on different synthesizers (e.g., a Piano on a Yamaha might be a Guitar on a Roland). The SC-55 standardized this mapping: roland sound canvas sc-55 soundfont