To make use of multiple SoundBanks, you need to make a few structural preparations like creating multiple scenes or Trigger Colliders. However, as a result, you will convert some of your fixed (constantly loaded) runtime memory into more flexible (load and unload when needed) runtime memory, which allows you to use the released runtime memory for other purposes. In the great scheme of things, keep in mind that loading ten 1 MB SoundBanks requires roughly the same amount of processing as loading one of 10 MB, so you will not be increasing your resource usage by separating your Events into more SoundBanks.