Here’s what they have to say about the update:
With iOS 7 just around the corner, we’ve just released an update to the Audiobus app that addresses some issues. We highly recommend updating now to stay compatible with our community of apps.
We’ve been working hard at Audiobus HQ on a significant Audiobus app update (among other things!). Keep your eyes peeled for these in our next update: Audiobus connection presets, multi-channel input device support, and a third thing that we’ll tell you about later on.
AudioBus is available in the App Store.