All three of these features would be huge for my games. Nesting folders in other folder would help with sorting. For example an SFX folder with different creature folders, or a music folder with locales and vibes. Volume sliders would be very useful in the Now Playing section so you can adjust what is playing without having to re-find it in your library. Search would also be great as sometimes you need to find a sound very quickly. I also don't like that when you are playing a playlist, clicking any other sound stops the playlist. For example, I'd like to play my "Dungeon Music" playlist in the background but then trigger FX on top like doors and monsters.