I have tried connecting an Alesis IO2 Express usb interface to my Ipad and setting the audio routing to use Headphone and Alesis outputs by selecting the combine button in settings. However, as soon as I combine both to use effectively the additional USB outs the headphone volume drops dramatically.
Is this a bug in the software or is it perhaps a compatability issue with the Alesis?
I have power going to both the Alesis and the Ipad, otherwise the Ipad will not recognise the Alesis as it does not supply enough power via the USB connection.