I've recently been asked what my thoughts on the Alesis IO Dock are. I had posted briefly about this before and despite it having a multitude of audio inputs and outputs, the issue for DJ apps is that it would not provide 2 independent stereo outputs (one for master and one for cueing).
The person that asked about the IO Dock has done some digging and uncovered this review which although states the outputs are separate - I think he means that you can control the volume of the outputs separately - rather than having 2 different stereo output signals - which is ideally what we all want from iOS.
I'm wondering if pressure from app developers can persuade Apple to at least consider altering iOS to allow 2 different stereo outputs from the device - one from the 30pin connector and one from the headphone socket. That really would be the ideal solution and would mean no more splitter cables, no MONO signal, no need to bluetooth / WiFi broadcast one stereo signal - all in all, a very neat solution.
My feeling is that if it were possible, Apple would have considered it already. In fact, it may not be just a limitation of iOS, but also the hardware involved too - in which case there would need to be a HUGE amount of pressure on Apple to change this in the product lines.
I wonder if any of the dev teams have already approach Apple about this? I always feel a little sorry for Anders at Algoriddim who appears to bear the brunt of user complaints about having to split the channels down to mono.