This might be handy for you …
Music2Bus is a music player compatible with Audiobus. You can send your Music (iPod) Library to all Audiobus compatible apps, and play them with various ways.
Audiobus (A Tasty Pixel) is the revolutionary new inter-app audio routing system, you can connect your Audiobus-compatible music apps together, just like virtual cables.
For example, You can play your favorite part of your favorite song in Apple GaraBand app, by using Music2Bus, Audiobus.
Additionally, 5-band equalizer is included.
Please note this app can not play protected music contents.
The app’s priced at $1.99.