Ashley I've tried something similar. This was all done when they were in the sound folder, with preload sounds set to off.
At first I tried loading all the music tracks on boot up. That failed, caused a crash.
Then I tried splitting up the preloading between the first 3 layouts. That failed, caused a crash.
Then I tried only preloading music when it was needed. That worked...for about the first 1/4 tracks. After that you could tell it was starting to bog everything down by having it all loaded into the memory, and eventually yes, caused a crash.
It's worth mentioning that Blitz uses roughly 20 music tracks. 14 of them are rather long, and definitely the ones causing issues. That being said if I could load/unload them 1 at a time I could make it work as these are the tracks that load in game, as opposed to during the menus.
I've tried many many solutions, and will continue to experiment. I don't want to make your life harder, but as it stands it's hindering me releasing Blitz on iOS (probably android too, but one thing at a time). As it stands I may just attempt to optimize the living hell out of it to get it running smoothly on cocoon.io, as the canvas+ webview fully supports preloading the music via the music folder (and uses .ogg as well, for what it's worth), but man it's a tiny bit frustrating to be so close and yet so far. I hope you understand!