Well, I think the entire point of a CLAS rig is that the idevice is being treated only as media storage. All the actual audio parts are then being done by the CLAS. What you want is something that can treat the DX50 as a storage device and then provide your balanced signals. OK - that's where the confusion ensued - I think I get it now.
I think if I was going to do this, I would probably just stick to an ios device instead of the DX50 - that provides the most choices (like the CEntrance that DrSheep mentioned), and since the idevice is just storage, it doesn't really matter - just like the specific laptop doesn't really matter to the audio chain once you have decided to use a USB DAC with the laptop.