I imagine it doesn't have any DAC. The DAC is still inside the phone, just like on previous iphone, the dongle is just a physical adapter to the 3.5mm standard.
I had assumed it had a DAC since I haven't seen apple use lightning for analog audio yet. I could be wrong, but couldn't find any source for clarification (upon googling). This slide from yesterday seems to suggest lightning is being used for digital out: https://cdn0.vox-cdn.com/thumbor/ghvFaov2v5hQ-mZ8y-r6VM5oTWI...