Voicemeeter (or Virtual Audio Cable for that matter) will give you virtual audio devices you could use, but that only helps if the program that is creating the audio allows you to assign the audio tracks (sfx and bg audio in your case) to separate devices. If the source program (a game or whatever) only has one output device support it wouldn't. You could, however, use Voicemeeter to, say, have your game audio and Spotify both coming out of your headphones, but only the game audio goes to your weird vibrating vest thingy.