Great sounding app, but needs background audio toggle – CMP Grand Piano Review

I intend to use this for performance. But the way it's set up, if I want to switch to another app for another set if performance sounds, I have to double tap home and kill this app in order to cut its background audio. They need a toggle for background audio in settings just like every other sound synth/module app has. And yeah... AudioBus support please!
Review by Arajara on CMP Grand Piano.