Huh, RPG Maker usually keeps playing a track that was playing when you load a save. I'm wondering what mistake they made... Well, whatever it is, I've thoroughly tested my own plugin. Currently-playing tracks will keep playing upon loading a save, and just to make things all the more convenient for developers, any tracks you preload should automatically preload again upon loading a save too!
And if you buy my plugin and have any problems anyway, let me know what happened and I'll do my best to fix it.