You know what would be awesome?
A card that has both a full XG and a full GS implementaion. two banks.
upon receiving a GS reset sysex, it switches to GS mode, using the Roland bank, with everything implemented by the sc55mkii, including the time variant filter to play sc55 composed techno midis properly.
Upon switching a XG reset it switches to XG mode, with a licensed XG wavebank equivalent to db50xg, and implementation of everything THAT card did.
Upon receiving a GM reset, it will reset in XG or GS mode, whichever one it's in. There's literally no working DWIM mode here, so that's the best compromise.
As for anyone who says XG is worthless and not worth the bother, final fantasy 7 pc says hi. 😀
AS for the licensing. here's is how i read it.
1) install onto soundcard=ok. roland made an scd-15 for this exact use case.
2) install into external usb case for use as an external synth on PC. also fine, even though you've essentially built your own sound module, which is an instrument. They neither can nor wish to prevent that particular use case. Even if you record the output and post that to youtube (D1M1 midi playback 🤣), it's still fine.
3) making it into a standalone midi module that can interface with a midi keyboard, and then using it as such. This is something they'd really rather you didn't do, but as long as you are just having fun in your own home, it's fair use, and they really can't stop you. Even if you use it to make music and record it, unless they have audio watermarks in the samples or something, they can't prove it. 😀 This will not get you in trouble, as a violation that's impossible to prove doesn't exist.
4) using the standalone module and the midi controller as touring gear? That will get you in trouble. You are supposed to buy the sound canvas itself, and this CAN be caught and you will be liable for damages.
5) selling this combination for less than a roland synth? You will get smacked down HARD for that one.
The important thing is if you are deliberately trying to avoid needing to pay for an actual roland synth or sound canvas for professional work, or actually trying to compete with roland's own offerings. as long as you are doing neither, you are fine. They aren't gonna fine you for jamming at home with your midi keyboard. 😀
Roland really aren't being evil here. I asked them about converting gm.dls for use with my awe32 back in the day, and was told that they really had no problem with that being done, as that's what those samples were licensed for (playback of midi on pc), but not to upload the converted file. they seem to have mellowed out a bit on that particular issue, judging by all the soundfonts still up and not DMCAed trying to fake a sound canvas. But they ARE likely to raise hell if a free emulator does show up for the SC55, and it doesn't require you to dump your own roms from your own sound canvas.