Apple iTouch - bypassing the internal DAC

I have the latest Apple iTouch and an Apple Camera adapter cable.  How can one pass the raw digital data to a DAC (McIntosh D150 pre or MAC6700 Receiver)?  I tried the USB A to USB B cable into the DAC but no go.
Miner - check out

Pretty certain I’ve seen related discussion for getting a digital stream out of mobile devices.

isn't there an optical output built into the headphone jack?