just to add a bit more detail. You can use a switch style node to take an input from outside the metasound and choose a different wave player with a different bank of assets. Would this get you what you wanted? After an enum is just an int underneath and can be converted into one and metasounds can take ints as inputs.
The downside of this approach being that this metasound will become very heavy. It is actually more desirable from a memory POV to have separate metasounds i would have though, especially if you were targeting a lower platform with less memory.