Just curious. Why are GM/XG and GM2 Voices even needed on a Genos or an SX?
Hi Larry --
Minimally, GM, XG and GM2 voices are part of GM, XG, GM2 compatibility. Specific, defined MIDI messages (continuous controller, System Exclusive) and effect types are also part of the standards.
Many existing Standard MIDI File songs depend on one of these compatibility standards. (Roland GS is yet another standard.) The main benefit to the user -- songs developed for a particular standard should sound the same on all platforms supporting that standard.
The cost in actual memory space is minimal (maybe 16MB to 32MB at the most). So, it costs next to nothing to include them in a factory sound set. Yamaha (Roland, Korg, etc.) invested a lot of effort getting them to sound decent (enough) while fitting into the small memories of yesteryear.
There's a few charmers in there. I still use the 60s Italian Organ in the GM2 sound set as a combo organ.
All the best -- pj