Uh... another idea:
how about snd_stop before level saving?

I understand you want it to keep playing the background music while loading a game, and just keep going with that music, not reload the last music.
(That's how I interpreted your "NO." Correct me if I'm wrong)

So your problem is that the current sound gets saved, but it shouldn't.
I searched the manual, and game_save does not say which part you need to deactivate in order to have it NOT save the sound.
I guess that leaves you with 3 options:
-stop the sound before saving, then it shouldn't load a sound when you call game_load. (not tested)
-stop the sound before loading, then it'll play the sound that it was playing when saving the game (not tested)
-try around with the game_save mode and see which one you need to deactivate if you DON'T want to save the sound. you could try a test level for that: loop a sound in main, then have a function that saves the game and one that loads it and use:
game_save("test",1,SV_ALL-SV_VARS);
Replace SV_VARS with the thing you don't wanna save.
i'd try SV_VARS, SV_SYS, SV_VIEWS, SV_FUNCTIONS and SV_LEVEL first.

No idea if this works. Hope it helps though.