Two things I'd LOVE to see for the audio feature...
1) ability to save/bookmark tracks for later (bonus if there's a note feature). Sometimes I'm looking for a track and come across one I like not for my current project, but want to save for another project later on.. I end up just writing down the name in my notes app, but would be great to be able to do this directly from Rush.

2) have soundtracks broken down further by type/category (maybe use hashtags?). For example, I'm looking for an "feel good" happy song with no lyrics. Sure I can use the search feature and find something that might work, but I really would like to browse Soundtrack>Instrumental>Road Trip or maybe I'm looking for something more dramatic Soundtrack>Instrumental>Epic