Apple iPhone DAC

I wanted to know whether or not the iPhone uses its own DAC to resample/compress music whenever it is played out of A) the Aux Port and B) the lightning port. I use the Aux port in my headphones for lossless audio and the lightning to HDMI (adapter from apple) to play lossless off my system. (I subscribe to TIDAL and recommend it). I've heard tell the iPhone does compress audio out of the AUX, but I'm not sure about the lightning port. This may be more of a question for an apple developer. Thanks for the help!